# Quad channel ram?



## PP Mguire (Aug 19, 2008)

According to this my buddy is running quad channel ram.






Quad would be 256bit right?
So if this is the case why is Nehalem triple channel and not native quad channel for one cpu?

Or is there something that im missing that needs to be said here.
I thought it was because he had 2 cpus that are both dual core. So 2x 2 dual channel controlers would be "quad pumped" not sought as "quad channel/256bit"

Explain?


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## zithe (Aug 19, 2008)

I'm confused too. You'd think the memory and the board would also need to be developed to run in 'quad channel'.


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## hbkl (Aug 19, 2008)

well im  more  confused  than yours   xD


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## Disparia (Aug 19, 2008)

zithe said:


> I'm confused too. You'd think the memory and the board would also need to be developed to run in 'quad channel'.



5000x chipset - it is developed for quad channel memory


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## zithe (Aug 19, 2008)

Jizzler said:


> 5000x chipset - it is developed for quad channel memory



That's a start. Now is there quad channel memory available yet?


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## PP Mguire (Aug 19, 2008)

This is a server board, server FB ram, and 2 server Xeons (obviously).

So its really quad channel? Cause if so im gonna feel like the biggest n00b ever.


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## ntdouglas (Aug 19, 2008)

He's running 8 gig at ddr2-533. Where's the timings at under the cpuz memory tab? And the channels box is greyed out. So no, he's not in duel channel either. What board is he running?


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## PP Mguire (Aug 19, 2008)

It says it in CPU-Z. Its a Dell server system that he stuffed some SCSI Cheetahs in and an 8800GT. He set the world record for that cpu at 2.6ghz as well.


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## Disparia (Aug 19, 2008)

PP Mguire said:


> This is a server board, server FB ram, and 2 server Xeons (obviously).
> 
> So its really quad channel? Cause if so im gonna feel like the biggest n00b ever.








The successor is the 5300 series of chipsets, supporting quad FB DDR2-800.

-edit- ^5400


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## PP Mguire (Aug 19, 2008)

I see. Well i spotted something horrible. 256bit memory interface but only a 64bit FSB. Thats like taking an interstate highway during rush hour and making it 2 lanes.


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## ntdouglas (Aug 19, 2008)

PP Mguire said:


> It says it in CPU-Z. Its a Dell server system that he stuffed some SCSI Cheetahs in and an 8800GT. He set the world record for that cpu at 2.6ghz as well.



Sorry, didn't see it was a server board. Just focusing on the ram. Not quite sure about the quad channel thing. Cpuz must not support that board then.


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## Mussels (Aug 19, 2008)

yeah its a server board with quad channel ram. the MHz and latencies are usually pretty poor for that kinda system however.


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## CrAsHnBuRnXp (Aug 19, 2008)

Quad channel is only Dual channel *2. A G.Skill rep told me cause I asked abotu this on another fourm. Heres the link. 

http://www.eggxpert.com/forums/thread/164031.aspx



> actually it is dual channel *2, not real quad channel
> 
> with the quad channel pack, we test the four sticks at the same time to avoid incompatibility
> 
> ...


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## Mussels (Aug 19, 2008)

the Gskill guy wont be talking about FBdimms in a server environment... he'd be talking about 4x1 or 4x2GB packs of ram


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## PP Mguire (Aug 19, 2008)

That guys isnt talking about the same thing we are though.


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## lemonadesoda (Aug 19, 2008)

Your friend *is* running Quad Channel.  Some server and workstation boards can also run Octochannel.  You need the very expensive chipsets to do this.  Memory bandwidth pwns a regular "consumer" mainboard. But FB-DIMMs are required: expensive and power hungry.

LOL@CrAsHnBuRnXp. The guy is refering to RAM kits, no capabilities of a mainboard.

Skulltrail is the nearest thing an "enthusiast" gets to specialist workstation performance: http://en.wikipedia.org/wiki/Intel_SkullTrail

Intel chipset 5400 allows for 800 clocked FBDIMMs. The older 5100 chipset only has 533 memory IIRC

http://www.asus.com/products.aspx?l1=3&l2=82&l3=644&l4=0&model=2090&modelmenu=1


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## Mussels (Aug 19, 2008)

thanks lemonade, well written post explaining the situation better than i did.


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## Deleted member 3 (Aug 19, 2008)

PP Mguire said:


> It says it in CPU-Z. Its a Dell server system that he stuffed some SCSI Cheetahs in and an 8800GT. He set the world record for that cpu at 2.6ghz as well.



It's a crap CPU though. And considering the chipset won't go past ~390MHz 2.6GHz won't happen.



Jizzler said:


> The successor is the 5300 series of chipsets, supporting quad FB DDR2-800.



There is no 5300 series. There is the 5400 Seaburg and the budget variation 5100. (uses reg DDR2 instead of FB)



zithe said:


> That's a start. Now is there quad channel memory available yet?



Channels are a chipset feature, not a memory feature. As far as the memory is concerned you can run it in 100 channel configurations. 



PP Mguire said:


> I see. Well i spotted something horrible. 256bit memory interface but only a 64bit FSB. Thats like taking an interstate highway during rush hour and making it 2 lanes.



Funny fact, the memory performs worse than dual channel DDR2. There are two FSB's, ie 2x 64bit. The memory is bottlenecking, not the FSB. 



ntdouglas said:


> He's running 8 gig at ddr2-533. Where's the timings at under the cpuz memory tab? And the channels box is greyed out. So no, he's not in duel channel either. What board is he running?



Timings are pretty much set for FB-DIMM's, latency is mostly cause by the AMB though. It's usually in the 80-100 area, pretty poor.


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## Deleted member 3 (Aug 19, 2008)

lemonadesoda said:


> lemonadesoda said:
> 
> 
> > Your friend *is* running Quad Channel.  Some server and workstation boards can also run Octochannel.  You need the very expensive chipsets to do this.  Memory bandwidth pwns a regular "consumer" mainboard. But FB-DIMMs are required: expensive and power hungry.
> ...


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## btarunr (Aug 19, 2008)

The older chipset is 5000 V/P/X.


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## lemonadesoda (Aug 19, 2008)

1./ FB-DIMMs "drink"!






2./ For Dan, http://en.wikipedia.org/wiki/UltraSPARC_T2. 4 independent FB-DIMM dual channel controllers = octochannel

3./ I had understood that the slower 5100 chipset with max FSB 333 was older than 5400 FSB 400. But perhaps as Dan suggested, it is the same generation, just came out first, slower, and cheaper? 

4./ FB-DIMM has a "rank" concept. Adding more memory to "ranks" of the same channel increases bandwidth. I think Dan would be able to explain the FB-DIMM technology better than me. But here's a link or two that explain, but infortunately, without real word benchmarking http://download.micron.com/pdf/techn...dr2/tn4721.pdf http://www.simmtester.com/PAGE/news/showpubnews.asp?where=533424&num=136

5./ Bandwidth on fully populated FB-DIMM server chipset pwns a regular dual channel DDR. Why? Quad channel vs. 2 channel, PLUS 2 rank vs. single, PLUS FB-DIMM allows SIMULTANEOUS read and write. Regular DDR cannot do this. Big gains when multitasking and/or tasking with mix read/write.  But latencies on regular DDR are lower. Swings and roundabouts depending on purpose.

NOTE >> Most reviewers who have tested bandwidth of FB-DIMM make the FATAL FLAW of using only 2 sticks. For max speed you need 8 sticks (4 channels populated, 2 ranks each). Plus, to see the real benefit you need to compare read/wriet benchmarks not just simplistic read only or write only. If anyone has a benchie or wants to hunt one down on the net... please link.


PERSONAL BET >> I'm pretty sure a xeon on quad channel FB-DIMM (2 rank even better) completing a video encoding task, e.g. MPEG2 to DIVX, would *STOMP *a similar Conroe DDR2 setup same clocks.


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## Deleted member 3 (Aug 19, 2008)

lemonadesoda said:


> 1./ For Dan, http://en.wikipedia.org/wiki/UltraSPARC_T2. 4 independent FB-DIMM dual channel controllers = octochannel


They are four separate controllers according to that text. I would imagine each two cores have their own controller, similar to how many servers have a memory interface per CPU. Look at high end Opteron boards for example. Those aren't quad/octo channel controllers, they simple have a controller per CPU.
The FB-DIMM specs allow six channels per controller, as far as I know there aren't any chipsets utilizing that though.
Anyway, I was assuming we were at least talking about x86 hardware, nobody has a modern Sparc at home.



lemonadesoda said:


> 2./ I had understood that the slower 5100 chipset with max FSB 333 was older than 5400 FSB 400. But perhaps as Dan suggested, it is the same generation, just slower, cheaper and lower power consumption, for blades?



Not per se for blades, though considering the 5100/5400 can waste quite some energy it might not be a bad plan to go for 5100 based blades.



lemonadesoda said:


> 3./ FB-DIMM has a "rank" concept. Adding more memory to "ranks" of the same channel increases bandwidth. I think Dan would be able to explain the FB-DIMM technology better than me. I've never seen it, but Dan's got a nice machine using it. He's the expert.



Most 1GB+ dimms are double rank modules in the first place. I've seen Wintec 4 rank modules as well. Look up some random post I made about ranks and quad channel with 6 modules. The ranks make this possible, same as dual channel with three modules. 



lemonadesoda said:


> 4./ Bandwidth on fully populated FB-DIMM server chipset pwns a regular dual channel DDR. But latencies on regular DDR are lower. Swings and roundabouts depending on purpose.
> 
> 
> NOTE >> Most reviewers who have tested bandwidth of FB-DIMM make the FATAL FLAW of using only 2 sticks. For max speed you need 4 sticks, ie. 4x 1GB >> 2x 2GB so that all channels are working. Even better to use 8 sticks so you have all channels are 2 ranks.  If anyone has a benchie or wants to hunt one down on the net... please link.



Yes, it's a fatal flaw. However, I still haven't seen any impressive numbers coming from FB-DIMMs, perhaps it is better when using 8 modules per channel with 4 rank modules. But this will be quite expensive and use a *lot* of power. 
Besides, my boards only have 6 DIMM slots (and just four on my server) so it's no option for me. I could eventually add two 4GB 4 rank modules though, that way I'd have 4 ranks per channel. (and 16GB of RAM, why would I want that?)


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## lemonadesoda (Aug 19, 2008)

I agree, FB-DIMM is not a winner for any price/performance or power/performance ratio.  But, on the simple question about which is faster, for a single threaded test, serial memory benchmark, regular DIMMs will win. But for multi-tasking mixed read/write, FB-DIMM wins.

> Games - DIMM
> Encoding, servers - FB-DIMM (but at a high price)

Academic study http://www.eng.umd.edu/~blj/papers/hpca2007.pdf

Decent, comparable, benchmarks of DDR2 vs. FB-DIMM, same processor family and clock, are IMPOSSIBLE to find :-(


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## btarunr (Aug 19, 2008)

Is this "oct-channel" ?


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## wolf2009 (Aug 19, 2008)

^^ WOW , what motherboard is that ? I'm sure its for a server, but how would it perform in video encoding and games ?


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## btarunr (Aug 19, 2008)

It is well, a server board. It's been on Newegg for over an year now: http://www.newegg.com/Product/Product.aspx?Item=N82E16813151089

Encoding: maybe good, Games: suck. Which game uses 16 threads lol.


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## Deleted member 3 (Aug 19, 2008)

btarunr said:


> Is this "oct-channel" ?



That's what I think the Sparcs do, have a controller per socket. It isn't exactly octo channel but it does dramatically boost memory bandwidth in AMD's case. So it isn't that relevant it isn't a single 8 channel controller.



lemonadesoda said:


> I agree, FB-DIMM is not a winner for any price/performance or power/performance ratio.  But, on the simple question about which is faster, for a single threaded test, serial memory benchmark, regular DIMMs will win. But for multi-tasking mixed read/write, FB-DIMM wins.
> 
> > Games - DIMM
> > Encoding, servers - FB-DIMM (but at a high price)
> ...



FB-DIMM's aren't as expensive as they used to be. Though I have yet to see a decent benchmark that shows the simultaneous read/write of FB-DIMM's are any good.
For instance, when I run Rightmark and set half the threads to read and half to write performance drops, which according to this theory shouldn't happen?
On the other hand, the lack of bandwidth of the current Xeons is hardly noticeable in every day use. So who cares?

That PDF only shows you need silly setups to get decent results. Besides, where did they get FBD-DDR3?


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## hat (Aug 19, 2008)

video encoding... pwn.
games not so much, only one pci-e slot. unless you stuck a card with two gpus on using the same pci-e connection

and yeah quad channel is a server thing. desktops don't really need anything more than dual, although nehalems tri channel looks interesting.


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## lemonadesoda (Aug 19, 2008)

Dan, are you running x4 (36bit) or x8 (72bit) FB-DIMMs? And do you know if this affects performance? I find the literature thin and unclear.

Also found some (not very thorough) reviews of FB-DIMM speeds scaling from 2 to 4 to 8 sticks.

http://www.phoronix.com/scan.php?page=article&item=495&num=1
http://www.phoronix.com/scan.php?page=article&item=606&num=1


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## btarunr (Aug 19, 2008)

Man, you really hate that _Last Edited By..._ thingy. 

Are Mac servers prettymuch just x86 servers with trusted platform modules + Mac OS ?


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## Deleted member 3 (Aug 19, 2008)

hat said:


> video encoding... pwn.
> games not so much, only one pci-e slot. unless you stuck a card with two gpus on using the same pci-e connection


Where do you get your information? Seaburg offers 36 or 40 PCIe 2.0 lanes (if those 4 lanes matter look it up )
Even Greencreek boards come with 2 x16 (gen1) slots in 16/4 configuration and has lanes spare for a x8 slot (not sure if there are x4 electrical, but still)



hat said:


> and yeah quad channel is a server thing. desktops don't really need anything more than dual, although nehalems tri channel looks interesting.



Quad channel (and FB-DIMMs as a whole) aren't primarily for performance, as they mostly fail there. They are made to load a system with RAM, 8 modules per channel are supported and up to six channels (four max for all current controllers). The gain in memory capacity is therefor huge, normal DDR2 memory allows two modules per channel which already causes issues in various cases, reg DDR2 allows slightly more but still lacks. So the idea of quad channel certainly isn't for servers, FB-DIMMs are.


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## Deleted member 3 (Aug 19, 2008)

lemonadesoda said:


> Dan, are you running x4 (36bit) or x8 (72bit) FB-DIMMs? And do you know if this affects performance? I find the literature thin and unclear.
> 
> Also found some (not very thorough) reviews of FB-DIMM speeds scaling from 2 to 4 to 8 sticks.
> 
> ...



I use x8 modules. Those benchmarks are from 2006 as well and seem even worse than the reality.


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## btarunr (Aug 19, 2008)

DanTheBanjoman said:


> Where do you get your information? Seaburg offers 36 or 40 PCIe 2.0 lanes (if those 4 lanes matter look it up )
> Even Greencreek boards come with 2 x16 (gen1) slots in 16/4 configuration and has lanes spare for a x8 slot (not sure if there are x4 electrical, but still)



He was commenting on that quad-1207 AMD board methinks. Wolf asked about how it would fare


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## Deleted member 3 (Aug 19, 2008)

btarunr said:


> He was commenting on that quad-1207 AMD board methinks. Wolf asked about how it would fare



Ah yes, that could just be true. In that case I'd argue that nobody buys a MP board for games.

Nice detail about AMD though, many of the older boards support newer CPU's, ie quads.


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## btarunr (Aug 19, 2008)

DanTheBanjoman said:


> Nice detail about AMD though, many of the older boards support newer CPU's, ie quads.



They (older boards) use the older HT link (2000 MT/s). DSDC kind of makes the CPU's share that bandwidth (you do have inter-socket communication though). Imagine the atrocities each little core faces when trying to make itself heard (in a crowd of 16). Builders should take note of that.


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## btarunr (Aug 20, 2008)

lemonadesoda said:
			
		

> PS... Do you enjoy reading *delete post correspondence!?*



I can't. It doesn't matter to me either. In fact I like your affinity to tidiness.


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