Throttlestop overclocking Desktop PCs

[Retrorockit]

It will be interesting to see if the W35xx, and W55xx unlocked Xeons can overclock as well as the QX6xxx, and QX9xxx CPUs. Most of the OEM computers that support those were DDR2 machines.
The i7 Extremes supported DDR3-1066, The unlocked Xeons DDR3-1333, and Hyperthreading Which the QX never had. The W5570/5580 have the added distinction of being unlocked 2x CPU, and also have the massive RAM capacity that server CPUs typically enjoy. Another question is whether 6 cores give ant adavantage in gaming vs. 4 cores.

 

[unclewebb]

The W5580 looks interesting. It supports DDR3-1333 memory.

https://ark.intel.com/products/37113/Intel-Xeon-Processor-W5580-8M-Cache-3_20-GHz-6_40-GTs-Intel-QPI

If it has an unlocked multiplier, a pair of them on a dual CPU socket board would be a lot of fun. 8 cores, 16 threads, perhaps 4.0 GHz. The ultimate retro rig.

I just tossed one in my EBay basket so someday I will be able to see what these are all about.

 

[Susquehannock]

Appreciate the explanation on these Xeons. Things have changed greatly since my days over clocking the snot out of low volt unlocked AMD T-breds. Fun times indeed.

Have W5590 in hand, and Panaflo fan to attach to a nice fresh lapped heatsink. With any luck I will be reporting back at 4ghz.

 

[Retrorockit]

Do you have any confirmed instances of newer CPUs being TS overclocked. I know TS supports these CPUs but a lot of people are skeptical about the overclocking aspect specifically. Sandy Bridge, Ivy Bridge, and Haswells. Even though LGA1366 is just as fast there seem to be a lot of "newer is better" mentality out there. I have no idea where to even start looking for unlocked Xeons in those "socket of the month" CPUs.

I did forget to mention the gorilla in the room. The 45nm 1366s did have the huge advantage of 3 channel memory support.

 

[unclewebb]

Some of the unlocked Sandy Bridge and up K series can be overclocked using ThrottleStop but these may be limited if a manufacturer has set a lock bit in the bios to disable this feature. I have not done any research on the 2nd Gen and up Xeon CPUs to see if any of them have unlocked multipliers. I wouldn't be surprised if they did. Sometimes the biggest difference between a Xeon CPU and a consumer grade CPU is the logo on the box that Intel sells it in. In other words, they are all produced on the same assembly line and are all virtually identical. Once a piece of silicon is manufactured, it is simple for Intel to program an on chip EPROM so the CPU knows if it is a Xeon, an Extreme, a K series or a regular CPU. They do not have separate buildings that only turn out Xeon CPUs or unlocked CPUs.

I know the original 4th Gen Haswell are all unlocked. The trick is that you will need to use a very early microcode to take advantage of this feature. With later microcode updates, only the K series will remain unlocked. Here is an example of a 4th Gen mobile CPU at 4900 MHz.

https://hwbot.org/submission/3091123_0.0_cpu_frequency_core_i7_4700mq_4900_mhz

This is not some top secret engineering sample. It is a fully locked CPU just like all of the rest of the MQ series. With the early microcode installed, the multiplier and MHz can be adjusted sky high. Not many people took advantage of this trick when it was discovered. Maybe people will be interested a few years from now when 4th Gen hardware is cheaper.

 

[agent_x007]

It will be interesting to see if the W35xx, and W55xx unlocked Xeons can overclock as well as the QX6xxx, and QX9xxx CPUs. Most of the OEM computers that support those were DDR2 machines.
The i7 Extremes supported DDR3-1066, The unlocked Xeons DDR3-1333, and Hyperthreading Which the QX never had. The W5570/5580 have the added distinction of being unlocked 2x CPU, and also have the massive RAM capacity that server CPUs typically enjoy. Another question is whether 6 cores give ant adavantage in gaming vs. 4 cores.

QX6xxx can't clock as good as QX9xxx or W35xx/W55xx because 45nm is simply a much better node for clocking.
All 45nm CPUs clock simmilary (up to a point), however there is that "silicon lottery" thing and "core revision" going on. You must keep in mind a basic fact : Bigger CPUs can't clock as high as smaller ones (on the same technology process [nm]).
True, Yorkfield is bigger transistor wise, BUT it has double core design (there are two small dies under IHS).
In Nehalems case (LGA 1366 45nm, example : "Bloomfield"), you have only one die, with a L3 cache, Hyper Threading, IMC and double QPI bus (one link disabled for desktop) - all attached on top of "normal" stuff present in Yorkfield.
Because ot this, Nehalems usually can't clock as high as 45nm Xeon's from older generation.

Do you have any confirmed instances of newer CPUs being TS overclocked. I know TS supports these CPUs but a lot of people are skeptical about the overclocking aspect specifically. Sandy Bridge, Ivy Bridge, and Haswells. Even though LGA1366 is just as fast there seem to be a lot of "newer is better" mentality out there. I have no idea where to even start looking for unlocked Xeons in those "socket of the month" CPUs.

I did forget to mention the gorilla in the room. The 45nm 1366s did have the huge advantage of 3 channel memory support.

Reason for it is simple : At that point (SB/IB), MB manufacturers Windows OC software got "good enough" and 3-rd party OC programs aren't needed that much (at least in majority of cases).
Triple Channel is present on all LGA 1366 CPUs, true. It adds 50% of bandwidth to any frequency your DRAM is using (vs. LGA 115x CPU).
However, it can't make AVX instructions work on Nehalem class CPUs, and getting LGA 1366 to clock 5GHz is hard, while Sandy can do it easily.
Also, clocking 12GB+ RAM over 2GHz with Triple Channel isn't "easy", and at that point you probably have to decrease UnCore frequency (which decreases IMC/L3 efficiency, which in turn wastes that added bandwidth).

PS. Throttlestop multiplier adjustment works on my 4960X, but without Vcore control (I'm using it with AI Suite installed and active)
Frequency calculator is messed up (I'm using Win 10 with Spectre/Meltdown patches active).

 

[Retrorockit]

The RAM clock doesn't change with TS multiplier overclocking. For better or for worse you're stuck at 1333FSB 3 channel. Some nice latency numbers are about all you can hope for.
The $20 Nehalems are kind of a curiosity compared to the 32nm Hexas. But at that price it will be interesting to see how the gaming benchmark score at 4 threads and 3 channel DDR3 1333 compares to the QX9650 Etc. Another difference is the heatspreader is larger on 1366. I've seen Intel list it as supporting 230W intermittent rating. Of course there's more stuff in there so who knows. The LGA775 are no longer much use for gaming. The Nehalem Xeons ?????

 

[Susquehannock]

Looks like this W5590 is locked. Other than changing default multiplier from 25 to 26T there seem to be no other changes available. Unless I am missing something.

 

[lexluthermiester]

The LGA775 are no longer much use for gaming.

That depends on the game. The really demanding games of the last year or so will give the upper end C2Q's a problem. But older games or even new games that don't stress a system too hard will still run well as long as good GPU is used.

Looks like this W5590 is locked. Other than changing default multiplier from 25 to 26T there seem to be no other changes available. Unless I am missing something.

That's still a decent performance boost as all cores can now run at their maximum.

 

[Retrorockit]

I found a W5580 runninhg 42x133 fsb at CPUZ. I never found a 5590 though.
http://valid.x86.fr/81teia
There are some settings, and limits that need to be raised in TS. On page 3 of this thread is a walkthrough for these CPUs. Also there is an UNLOCK button. It says what it will do, not what it's doing. It says LOCK when the CPU is unlocked, UNLOCK when the CPU is locked. There are a few things that need resetting after that. There is no VCORE setting, it's all very indirect. It's not as straightforward as LGA775 was. Intels scheme was to let you raise multi/power limits but they retain throttling control related to temperature.

I can't find the article about the unlocked W3570/80 that said the W5580/90 were unlocked also. If I find it I'll link to it. Just the article, and 1 42x133 multiplier overclock.
I found a thread on XTU overclocking an HP Z400 at Overclockers.com.
http://www.overclockers.com/forums/...n-w3680-cpu-with-intel-extreme-tuning-utility

I found an article on the W55xx CPUs that says RAM speed varies with number of 3 channel sockets populated on the MB. It also shows performance relative to harperstown Xeons, But FBDIMMs were part fo that situation also.
https://techreport.com/review/16656/intel-xeon-w5580-processors

 

[unclewebb]

I found a W5580 runninhg 42x133 fsb at CPUZ.

There is only that single CPU-Z post showing a W5580 with a high multiplier so I am not yet convinced. That validation shows a couple of things that do not look right. It shows the Min multiplier as 12 which is right and it shows the Max multiplier as 26 but the current multiplier is 42. Either 26 is not the maximum multiplier or the current multiplier is not 42. The next thing that is not quite right is the CPU is running at 5612 MHz but the Core Voltage is only showing 1.216 Volts. That is definitely not right. You need way more than 1.2 V to run stable enough for a CPU-Z validation at 5612 MHz.

The ThrottleStop LOCK / UNLOCK button is only available when you have an unlocked Core 2 Duo Extreme CPU. If the W5580 / W5590 is unlocked, a person would need to click on the TRL button and would need to increase the turbo limits higher. This previous post in this thread shows what the Turbo Ratio Limits (TRL) window looks like when running on a Core i processor.

https://www.techpowerup.com/forums/threads/throttlestop-overclocking-desktop-pcs.235975/post-3799652

If those triangular shaped adjusters are grayed out then that means this feature is not available.

I will do some testing when my W5580, $20 special from China arrives.

W5590 Default Multipliers
Turbo Boost Disabled - 25
1 Core Active - 27
2 Cores Active - 26
3 Cores Active - 26
4 Cores Active - 26

W5580 Default Multipliers
Turbo Boost Disabled - 24
1 Core Active - 26
2 Cores Active - 25
3 Cores Active - 25
4 Cores Active - 25

 

[Upowa]

I know the original 4th Gen Haswell are all unlocked. The trick is that you will need to use a very early microcode to take advantage of this feature. With later microcode updates, only the K series will remain unlocked.

Hello, new here. I have a Dell T3500 and Supermicro X8STi with no means to BCLK overclock. The T3500 had two different clock generators, I was hoping to get the one I could change with setfsb but was sent the other board. The X8sti has tweakable clockgen but seems pretty locked down beyond a couple of mhz. My only option would be to drop in an unlocked cpu, which is how I found this thread. Fortunately, the 4 core xeon nehalem cpus are cheap these days. I still looking for an oem lga1366 board that can blck overclock because I don't want to pay over $150 bucks for one that can. And I already have a 6 core westmere and 2 nehalems.

Getting to uclewebb's point that the haswell are unlocked which they aren't. It is in that one particular case with the i7 mobile cpu that has a bug to allows for higher multipliers. The other haswell are locked, but are able to get all cores working @ max turbo mode with an earlier microcode. I've actually done this for a few desktop haswell with microcode 07 or earlier. I guess it works on mobile haswells as well, the i5 seems to have their own set of mobile microcode. The i7 hq mq cpus seem to use desktop microcode. That bugs seems to only work with haswell that have overclockable turbo bins. H-series desktop haswell boards can be overclock through bios modding as well.

hwbot example E5-1650 v2 (ok not haswell but still)

hwbot example i7-4700MQ

Also, you'll need a motherboard that comes with an amibios to mod which is easiest way to change the microcode. You can the microcode in a bios through hex editor if you know what your looking for. An external bios programmer comes in handy as well in case you mess up and internal flashers aren't always reliable as bios can be lock in certain areas. Also, laptop motherboard don't come with components to sustain such high frequencies that will sustain high cpu loads, you'll most likely fry the vrms if you aren't careful. Overclocking the mobile haswell i7 will be my next project when I can afford to.

 

[Retrorockit]

The W5580 in 2nd place shows 0V. so CPUZ seems to have an issue sometimes. The Uncore speeds differ between the first 2 results, and seems to reflect the multiplier overclock vs the fsb overclock in that the fsb one is higher. They're both at 20xfsb. The one Dell further down the list has no Voltage at all. At that speed it could be dry ice changing the resistance and allowing lower Voltage. IDK much about that though, just guessing.
http://valid.x86.fr/top-cpu/496e746...0202020202020573535383020204020332e323047487a

I found this thread on unlocked Xeons. They seem to start with Westmeres/ Gulftowns, no Nehalems mentioned. But lots of newer ones.
https://forums.servethehome.com/index.php?threads/xeons-with-an-open-multiplier.15983/

I noticed a couple of the top results on the CPUZ W3570 chart are identified as W3565. Maybe another unlocked Haswell? At Ark Intel all I see different is lower Voltage and slower memory speed.
https://ark.intel.com/products/39721/Intel-Xeon-Processor-W3565-8M-Cache-3_20-GHz-4_80-GTs-Intel-QPI
https://ark.intel.com/products/39722/Intel-Xeon-Processor-W3570-8M-Cache-3_20-GHz-6_40-GTs-Intel-QPI

 

[Susquehannock]

The triangle adjusters in both TRL and TPL are all greyed out so this W5590 is definitely locked. Even so, changing the multiplier to 26T did give a nice little performance boost. 13.297 to 13.055 in TS bench.

You have inspired me to try TS with some of my W3565 that are collecting dust.

[edit]
Regarding heat .... have only been able to run a few Xeon 1366 chips so far. W3565, W5590, and X5687. All 130w TDP. In this very limited sampling, seems the 45nm chips run about 15-20c hotter under 100% load than the 32nm.

 

[lexluthermiester]

seems the 45nm chips run about 15-20c hotter under 100% load than the 32nm.

That's about on par. The 32nm CPU's run cooler as a rule compared to 45nm parts running at the same speeds.

 

[Retrorockit]

The claim that W5580/90 were unlocked was made in an article by professional hardware testers. The article was about the single core W3570/80. Maybe the tester didn't take into account that they may have received ES (engineering sample) CPUs. The W5580 at CPUZ is listed as a retail CPU. Hmmmmmmm.
I was looking at a W3570 club and they made much ado about batch numbers. But I didn't see anything related to some batches being locked, or unlocked. Just which ones overclocked better.

I found this Throttlestop aware thread at Dell community forums. He lists the usual unlocked Xeons W3680,W3690,W3570,W3580, and further states the W5580,W5590 are not unlocked.
https://www.dell.com/community/Desk...compatible-processor-list/td-p/4101387/page/3
I finally rediscovered the article that got me looking into the 2 CPU unlocked question.
https://www.theinquirer.net/inquirer/review/1531023/intel-xeon-w3580-cpu-asus-p6t7-ws-mainboard

 

[unclewebb]

Spec wise, the W3570 is almost identical to the Core i7-965 Extreme and the W3580 is almost identical to the Core i7-975 Extreme. Both of the Extreme processors have an unlocked multiplier so it makes sense that the W3570 / W3580 also have an unlocked multiplier. The main difference is the rated memory multiplier available which is higher for the Xeons. If these CPUs are all unlocked, the rated memory speed doesn't really matter because with the right bios, you should be able to adjust the memory multiplier to whatever you like.

For the 6 core CPUs, the W3680 and the Core i7-980X Extreme look like twins on paper and so do the W3690 and the Core i7-990X Extreme. This is typical Intel. They try to create multiple models out of a single design.

The Core i7-970 and W3670 are another set of twins. The Core i7-970 has a locked multiplier and so does the W3670 that I tested.

The claim that W5580/90 were unlocked...

I think if these 2 were unlocked, there would be more evidence posted somewhere on the internet. I plan to put my new W5580 in to both my X58 motherboards to see if either one shows it as unlocked. If not, it has a nice high multiplier so some BCLK overclocking should allow it to show its stuff.

changing the multiplier to 26T did give a nice little performance boost

The T stands for turbo mode so that bumps up the multiplier from 25 to 26. When turbo is enabled, you need to enable C3 or C6 in the bios so the CPU can access the 27 multiplier. A 1 thread TS Bench test is useful to see if your CPU is using the 27 multiplier or not.

seems the 45nm chips run about 15-20c hotter under 100% load than the 32nm

That's what I remember when the 32nm first came out. Big drop in heat which allowed easier and higher overclocking.

 

[Retrorockit]

Hello, new here. I have a Dell T3500 and Supermicro X8STi with no means to BCLK overclock. The T3500 had two different clock generators, I was hoping to get the one I could change with setfsb but was sent the other board.

There were 4 different T3500 MBs. I have no idea what the differences were, I've just seen that many different part#s looking at them online. What PLLs have you seen? SetFSB doesn't do much without increased Voltage, and the way you get that is Throttlestop and an unlocked CPU. But FSB changes disrupt so many other things you won't have control over that I consider not doing it an advantage. But a lot of people are comfortable with it so to each his own.

I think if these 2 were unlocked, there would be more evidence posted somewhere on the internet. I plan to put my new W5580 in to both my X58 motherboards to see if either one shows it as unlocked. If not, it has a nice high multiplier so some BCLK overclocking should allow it to show its stuff.

When overclocking Dells there are 2 things I've learned. Ignore everyone who says it can't be done. The other is try every damn thing you can think of. I've always been amazed that everyone at OCN is nuts over X5670 CPUs and ignores the W3680/90 unlocked versions. I've never even heard of the W5580/90 mentioned anywhere. The first thing I did read was they were unlocked. 42X133 @CPUZ made quite an impression also. But I guess the Nehalems get overlooked in favor of the 6 cores. Too bad they didn't make 32nm 4 cores in LGA1366.

 

[unclewebb]

The guys on OCN usually have boards that allow BCLK overclocking so for them, the X5670 is fine. I prefer the W3680. It is the same price or slightly cheaper on EBay and the unlocked multiplier in the W3680 is more flexible. The X5670 has a higher memory limit but 24GB is not going to limit the majority of W3680 desktop users.

I had a look on HWBOT at all of the W5580 / W5590 high scores and I only found one CPU with a higher than default multiplier.

http://hwbot.org/submission/872171_v2_v3_cpu_frequency_xeon_w5580_4793_mhz/

If you look a little closer at this entry you will see that it is not actually a W5580. Intel writes CPU model information directly to each CPU and this information is displayed in the CPU-Z Specification box. This box shows model 000 which is typical for an early ES (Engineering Sample). When CPU-Z is not sure, it will use a look up table and try to guess what model a CPU really is. This information is displayed in the CPU-Z Processor Name box at the top. That is the opinion of CPU-Z but it is not Intel's opinion. Early ES processors can have characteristics of 2 different future retail processors but may not be exactly the same as any retail processor. Calling one of these things a W5580 is wrong.

If the retail W5580 / W5590 have an unlocked multiplier, it is very unusual that there is not a single legit entry on HWBOT showing this capability.

Edit - For comparison, 9 out of the top 10 HWBOT entries for the W3680 show evidence of an unlocked multiplier. The top 6 are all over 6000 MHz. Who wouldn't want one of these things? Not a single X5670 is over 6000 MHz. Why? Its locked multiplier requires a sky high BCLK which is not possible. Unlocked multiplier FTW!

 

[Upowa]

There were 4 different T3500 MBs... What PLLs have you seen? SetFSB doesn't do much without increased Voltage, and the way you get that is Throttlestop and an unlocked CPU. But FSB changes disrupt so many other things you won't have control over that I consider not doing it an advantage. But a lot of people are comfortable with it so to each his own.

What bclk overclocking allows for is to overclock the memory as well, which is the only way to go beyond 1333mhz. The timing for other components are unchanged AFIK. The T3500 I have came with a SLG8XP519T clock generator which has no clock lookup table, I was hoping to get the one with CV183APAG clockgen. I've had success with a Dell Inspiron 580 lga1156 bclk overclocking it beyond 166mhz with the CV183APAG clockgen. There are a few lga1366 boards with a tweakable clockgen including the Z400, lenovo s20 (only 1 of 2 varients), & the Dell Studio 435mt/9100 which seems to have the most promise for bclk overclocking. Getting 4ghz is pretty easy on most CPUs bumping up the FSB to 166mhz.

What is frustrating is that the X8sti board seems to not allow for bclk overclocking but it should be fully capable of doing. I even went as far as pin modding the PLL, and no go there as well for the T3500 or X8sti. I may find some more luck with the other lga1366 boards when I can get my hands on them. I think these bios can be modded to allow for higher multipliers with an unlock cpu. You can change the default the turbo multiplier in the bios to your desired setting and boot up with it, possibly. I'll have to see if that is possible once I get a unlocked cpu. Not sure what to go with a W3670 or a W5580, the latter is a few bucks more. Maybe the W5580 to see if it is in fact unlocked or not. I have a dual cpu lga1366 board I've yet to play with as well.

Also, Anyone have any experience with the Dell T5500 boards? They seem to have a tweakable PLL. Are they a bit better quality than the T3500? Next month, I'll be able to get another board to test out.

 

[Retrorockit]

It's looking like the W5580/90 aren't going to be unlocked. I did see reports of unlocked ES versions so that's probably where the rumor got started. Since the W3680/90 are routinely ignored I thought maybe the W5580/90 were also. I guess they're just ignored for being Nehalems.

What bclk overclocking allows for is to overclock the memory as well, which is the only way to go beyond 1333mhz. The timing for other components are unchanged AFIK. The T3500 I have came with a SLG8XP519T clock generator which has no clock lookup table, I was hoping to get the one with CV183APAG clockgen. I've had success with a Dell Inspiron 580 lga1156 bclk overclocking it beyond 166mhz with the CV183APAG clockgen. There are a few lga1366 boards with a tweakable clockgen including the Z400, lenovo s20 (only 1 of 2 varients), & the Dell Studio 435mt/9100 which seems to have the most promise for bclk overclocking. Getting 4ghz is pretty easy on most CPUs bumping up the FSB to 166mhz.

The SLG8XP519T is what mine has. I think it's shared with the Optiplex 760, and I've seen reports that there are a couple other compatible PLLs that can access settings in SetFSB. The suggestion was to load some other PLL and see what reports the FSB correctly and try the settings. I guess the theory is if itread correctly it can write correctly also. Throttlestop overclocking doesn't change the FSB at all. It unlocks the multiplier, and Voltage. This allows the use of MB that have locked PLL chips, and no BIOS options, like the T3500 which would otherwise be useless. It also produces very stable and useful overclocks. My Dimension E520 with a PLL locked to 266fsb, and no BIOS options was #2 at CPUZ for almost 2 tears with a QX6800 at just under 4GHz. with aTS overclock. if it hadn't died from capacitor rot I would downclock the PLL and add another multiplier and tweak it a little higher to get back a spot or 2. But I don't feel like building another 12 year old computer right now. Have you tried Throttlestop and a confirmed unlocked CPU yet? It's nice to know the Z400 has some options for the FSB crowd. The T3500 is a tough nut to crack for FSB overclocking, and a piece of cake for TS method.
As Unclewebb stated above it's not uncommon to see much higher overclocks with unlocked CPUs. That can make up for a few Mhz of RAM timing. Of course some people will want both

Also, Anyone have any experience with the Dell T5500 boards? They seem to have a tweakable PLL. Are they a bit better quality than the T3500? Next month, I'll be able to get another board to test out.

The T5500 has an optional riser for a 2nd CPU, and added memory slots on a daughter board. This requires a 2nd 8 pin CPU cable. They may share some PSUs with the T3500 but need different modular cables depending on CPU,GPU configurations. Because of dual CPU support they aren't X58 chipset. I have no first hand with those, just what I gather from window shopping. Might be a good OC platform in single CPU mode. Reading the service manual at Dell Support can let you know about any other oddball features it may have.

 

[Upowa]

Too bad they didn't make 32nm 4 cores in LGA1366.

In fact they did:
"Westmere-EP" (32 nm) Efficient Performance

Have you tried Throttlestop and a confirmed unlocked CPU yet?

I have tried Throttlestop, but haven't been able to utilize it as much as I would hope for. I really only have one unlocked haswell K processor on a board with overclocking in bios. All other cpu's I have are locked so FSB overclocking is essential like with skylake cpus and everything before sandy bridge. Throttlestop seem to be most useful with unlocked cpu's on oem boards. I definitely would like to build a E5-1650 v2 system when those prices come down a bit because the ryzen 1600 builds are roughly the same price. That is kind of why I'm playing with these older system with the performance matching newer system at a third of the cost.

I'm more interested in the hardware in seeing how much performance I can get out of them. I'm not an extreme overclocker by any means. I'll get an unlock cpu next month whether it be the W3570 or the W5580 4-core nehalem and see what these boards can do. I'm still in search for a lga1366 oem board with fsb overclocking even when the unlock cpus aren't that expensive. I'll report back with my findings as soon as I get a chance.

 

[Retrorockit]

While aftermarket PSUs can be used in these Dells you need to be sure they have enough 5V. and 3.3V. power. Check this on your original PSU label. EVGA has some that have enough power there.

 

[Susquehannock]

Always wanted to run a T5500 board. received one (bottom image) from same source as these T3500 boxes. Could not get it to post, sadly. Probably why it was headed for the dumpster.

Fits in the T3500 box perfectly. Besides slot sizes and CPU riser they are quite similar, with one key difference. Instead of X58 the T5500 is based on the Intel 5520 chipset. And unlike the T3500, they will accept buffered/registered ECC RAM which are cheap and plentiful. 48gb would be nice for video editing.

[edit]
Aftermarket PSU do indeed fit into the T3500. Have replaced with 550w Seasonic G series on occasion. Just have to bend the upper retaining tabs on case ceiling flat so it will sit flush. Only concern was smaller value on 5-vsb rail (2.5A vs 4.0A). Which as I understand is used for power in standby mode in a networking environment. Being a gaming box it was not an issue.

 

[Retrorockit]

The W5580 is turning out to be a locked CPU. A comment in an article, and a CPUZ multiplier overclock got me looking at it but it's not true for retail CPUs.

In the X58 Xeon club at OCN a lot of people are getting 48GB to run on X58 boards with 1366 Xeons. I'm not sure if it's just the dual CPU Xeons that allow this or if the unlocked W3xxx can do it also.