ATI 4850 Overclock Results

[Chezz]

Here is a closer pic of the volt mod wiring without the voltage regulators plugged in.

 

[BraveSoul]

just squeezed the fan between heatsink and sound card. stiff like glued. those r the highest clocks. and it just hung up while FurMark stress testing.temps get to 80c on GPU and VRM too hot? or too much speed...doesnt crash in games, wierd. \you said 2.2 volts on memory not recommended y?

 

[SnyperBob]

ok, I'm sure there's tons of info out there about irons, but what soldering iron do you recommend for work this guys?

I've had nothing but trouble with craptastic radio shack ones and those stupid cold heat ones. I realize I need a pencil tip for an iron, but what kind or irons are you using?

I'm going to try to do some poking around and see what everyone recommends.

Thanks Chezz for the new picture, that really shows it all. And thanks for the explan.

 

[SnyperBob]

Oh, and Chezz, did you also do the pencil mod for your card, or is that not needed with the 'hard wire' mods you did.

What kind of scores are you getting with your mods compared to a stock card? You have quite the system in your specs. Thanks

 

[Chezz]

Oh, and Chezz, did you also do the pencil mod for your card, or is that not needed with the 'hard wire' mods you did.

What kind of scores are you getting with your mods compared to a stock card? You have quite the system in your specs. Thanks

No, you do not do both mods. The pencil mod is for people not comfortable with soldering and is also advantageous in that you can easily reverse the overvolt by "erasing" the pencil mark.

They both accomplish the same thing however I do not recommend the pencil mod from my own personal experience. The carbon in the pencil creates a parallel circuit similar to the variable resistor, so as you could imagine the results are unpredictable and overtime it may not maintain it's initial resistance value.

My first volt mod attempt on my 4850 was the pencil mod. After doing the mem volt mod my computer wouldn't boot, so I had to erase the mod and everything was fine again. I believe the pencil mark may have had too low of a resistance thus overvolting my memory circuit.

After having the pencil mod problem, I ran a test to see how much a pencil mark resistance can vary. I took a pencil and wrote several lines on paper, a CD case, and another rougher piece of plastic; the results varied drastically (this is when I decided to do the solder mod). The pencil mark resistance can also vary drastically depending on pencil "lead" type (2H, B, etc...), pencil manufacturer, and how hard you press the pencil.

For soldering I used a variable temperature 50 watt soldering iron. I made most solder joints at 500 to 600 degrees F. Here is a link to the iron I used: http://www.mcmelectronics.com/product/21-6765

As for performance gains - here are some stats:

3DMark06

Stock ASUS 4850
GPU: 625 Mhz
Mem: 993 Mhz
3DMark06 Score: 12337

Overclocked ASUS 4850
GPU: 800 Mhz
Mem: 1100 Mhz
3DMark06 Score: 14270

Crysis Benchmark Tool Frames Per Second - High Settings, 3 runs @ 1280x1024

Stock ASUS 4850
GPU: 625 Mhz
Mem: 993 Mhz

No AA: 46.58 fps
2x AA: 37.51 fps
4x AA: 36.07 fps
8x AA: 37.505 fps
16 AA: 37.495 fps


Overclocked ASUS 4850
GPU: 800 Mhz
Mem: 1100 Mhz

No AA: 56.21 fps
2x AA: 44.655 fps
4x AA: 42.915 fps
8x AA: 44.835 fps
16 AA: 44.82 fps

 

[Chezz]

...you said 2.2 volts on memory not recommended y?

I had heard around in other forums that the manufacturer's maximum recommended voltage value was 2.2 volts and based on my own experiences, above 2.1 volts did not buy me anything. About 2.07 Volts is what I have been hearing to be the sweet spot.

I decided to do my own research and found the memory manufacturer's spec sheet (see attached). After looking at the spec sheet I would personally stay at 2.2 or below unless you watercool your memory chips. They say the maximum recommended voltage is 2.1 volts, however the absolute maximum is 2.5 volts, but they don't specify at what maximum temperature using 2.5V??? Of course, as overclockers we do not always follow the rules...

What is your voltage BraveSoul?

 

[cp#]

700/1100 here with an Accelero S1

I joined a TF2 server earlier today and forgot about it.. when I came back into the room a few hours later I saw a solid green screen. In theory it would have only been displaying the server greeting or team menu... nothing graphically intensive. I reset the PC and ran a minute of ATI artifact tool (no errors) then played TF2 with no problems for 2 hours.

 

[SnyperBob]

wow, thanks Chezz, sorry for all the questions but it seems like you really know your stuff and can/are willing to explain things to us n00bs. lol. A lot of the other forums ppl just disregard the simple questions.

Can you give some info about the variable resistors? Did you just pick them up at a local store, or did you order them online somewhere. Are there different types? Yours are blue. I've also seen ppl use white ones and I think yellow ones as well.

Do the colors indicate the rating of the resistor? ie...blue ones are 100k?

Also, are there specific ratings that I need to buy? I've read about 24 turn ones, 15 turn ones, I've read for the 4870 mods, to wire 10 ohm resistors in series in case the variable resistor takes a dump and goes to zero or something. I've not seen any mention the 10 ohm for the 4850 however.

Are the VRs you used called horizontal or vertical mount?

Also, in regards to the variable resistors, is there a certain watt one that is needed? I guess if you could link me to where i could buy these resistors with all the correct specs, that might be easiest.

Sorry for all the questions, I'm just trying to not blow the card up and lose $200 on this, lol.

I picked up a gfxchilla and I have two 80 mm fans on their way to upgrade the gfxchilla. I won't do any hard mods over 1.2 with the stock cooler. I'll wait until I can get the gfxchilla mounted so I don't fry the card.

Thanks for the link to the soldering iron. This looks like what I need. I always wanted one you can just dial in the temp and the price is right. I've seen digital versions of the one you linked (I think it was a weller) and it was well over $100 IIRC.

 

[SnyperBob]

I have another question about vGPU voltage mod. Right now my card is stock and I'm trying to see how far I can get with just bios mods.

I just picked up a MM, and have yet to check the card's actual VGPU measurement. Do I want to match the bios vgpu voltage to what my card physically measures?

I downloaded a bios that was for 1.2 volts. I tried it on my stock card and didn't very far. I could only run at 700/1000 for one test and then it didn't work anymore. I edited the same bios to 1.18 volts (I read that is around where a stock card reads), because I didn't have a MM yet to measure. I seemed to get better results running bios at 1.18 volts.

Ok, so I guess my question is.....do I need to match the voltage in the bios I flash on to the card with what the VGPU is on the card (measured with a MM)? I'm trying to get the bigger picture on what all this means.

So if I go home and measure my cards VGPU as 1.17 under load, I should flash the card with 1.17 volts in the bios?

 

[Chezz]

...Can you give some info about the variable resistors? Did you just pick them up at a local store, or did you order them online somewhere...

Glad I could help. I purchased the resistors at a local electronics store. I bought a Philmore P/N: 68-104 100k ohm variable resistor. Here is a link: http://www.philmore-datak.com/mc/Page 267.pdf.

As for adding a 10 ohm resistor on the 4850, it probably is not a bad idea, but I am not sure if 10 ohms would be enough to protect the circuit. It wouldn't take much to calculate the resistance required to protect the 4850; however, I am too much of a cowboy to implement such safety measures (I'll get back to you in a couple of months when my card burns out...I will just have to go buy a 4870 X2).

I am not exactly sure what type of power the variable resistor will see and I am no Electrical Engineer, but I believe everything we are tapping into for the volt mod is on the low current side of the power circuit. My guess is by changing the resistance we are changing a time constant that controls the voltage regulator. Anyone know for sure what it does?

One VERY important thing to note again that was brought up before - you need to make sure the chips to the right of the memory on the end of the card (I believe they are voltage regulators) are cooled very well. I most of my GPU overclocking limitation appears to be due to these chips. I regret it now, but I used arctic thermal epoxy (there is no going back from that) and mounted some Swiftech style copper RAM sinks on the chips. Believe it or not even with the fan directly on the sinks the temps are still outrageous. If I could do it again I would have put a much larger sink. Go big on the sink...

 

[Chezz]

...Ok, so I guess my question is.....do I need to match the voltage in the bios I flash on to the card with what the VGPU is on the card (measured with a MM)? I'm trying to get the bigger picture on what all this means...

I forgot to answer this part of your question, so here is the answer...

Using the 100k ohm vr will increase the GPU voltage above the values in your Bios - it's additive. Thus, if you decrease the Bios voltage values your modified volts too will decrease.

I put my Bios voltage at 1.3 volts for the overclocked states. About 1.2 volts is the max most cards will put out, so I left it at 1.3 to make sure it was at it's max voltage.

The one thing to note is in the 2D, low clock speed, states the voltage will too increase from the 100K ohm volt mod, so you may want to drop your 2D state voltages in the Bios after the volt mod in order to compensate. It is not necessary, but why hit your GPU with 1.2 volts running at 500 Mhz when all it needs is 1 volt...

Our discussions have moved away from the original thread...anyone know how to move old posts to a new thread?

 

[SnyperBob]

One VERY important thing to note again that was brought up before - you need to make sure the chips to the right of the memory on the end of the card (I believe they are voltage regulators) are cooled very well. I most of my GPU overclocking limitation appears to be due to these chips. I regret it now, but I used arctic thermal epoxy (there is no going back from that) and mounted some Swiftech style copper RAM sinks on the chips. Believe it or not even with the fan directly on the sinks the temps are still outrageous. If I could do it again I would have put a much larger sink. Go big on the sink...

I've heard people sawing the ram heatsink off of the stock cooler/sink and reusing that with an aftermarket GPU cooler. Not sure how well that would work, I'm sure you would still need a dedicated fan to the ram

Would you recommend using thermal tape then, instead of epoxy in case I need to remove the heatsink? I don't mind spending a little more for the tape if it'll saev me from destroying the card if a specific heat sink doesn't work well...

 

[Chezz]

I've heard people sawing the ram heatsink off of the stock cooler/sink and reusing that with an aftermarket GPU cooler... Would you recommend using thermal tape then, instead of epoxy in case I need to remove the heatsink?...

I originally did just that, sawed off the VR heatsink and kept the original thermal tape and reused it. I never measured the temperature on that heatsink, so I can not compare it to my ram sinks I am currently using.

My main reason for going with the ram sinks is they have a greater cooling surface area directly above the VRs; however, the stock sink probably has a greater surface area overall. The other advantage I saw with the ram sinks is I could use epoxy which if applied right should have better thermal properties than tape (spread thin). With the stock sink, epoxy may not work too well because it is hard to make up for any height tolerance issues between chips and you may end up with poor surface contact on the chips.

 

[cp#]

Had a hard freeze in TF2 tonight right after joining a server. About an hour earlier I had played for 2 hours with no problems. I backed down the RAM to 1000. I also have that annoying high pitched whining when the GPU is under load.. probably the VRMs or a capacitor. Any remedies?

 

[phanbuey]

Had a hard freeze in TF2 tonight right after joining a server. About an hour earlier I had played for 2 hours with no problems. I backed down the RAM to 1000. I also have that annoying high pitched whining when the GPU is under load.. probably the VRMs or a capacitor. Any remedies?

lol... that is really common with the GT200 nvidia cards. Mine whines so loud i cant fold when i sleep.

 

[SnyperBob]

Had a hard freeze in TF2 tonight right after joining a server. About an hour earlier I had played for 2 hours with no problems. I backed down the RAM to 1000. I also have that annoying high pitched whining when the GPU is under load.. probably the VRMs or a capacitor. Any remedies?

Are you on the stock cooler? Is it your stock or aftermarket fan that you think is the culprit?

 

[mYrAn]

Can you calculate what voltage you have? Ive done the 2nd pencil mod, the one where you draw on the PCB, and i went from 5.12ohm to about 4. My multimeter always jumps from like 1.3 to 1.4, so i dont know my exact voltage. So, is there a way to calculate what voltage my core is getting by having the ohm? Thanks in advance!

 

[cp#]

Are you on the stock cooler? Is it your stock or aftermarket fan that you think is the culprit?

Accelero S1 with two 120mm fans. Load temps are in the high 40s, low 50s so I doubt it is that.

 

[Chezz]

Can you calculate what voltage you have? Ive done the 2nd pencil mod, the one where you draw on the PCB, and i went from 5.12ohm to about 4. My multimeter always jumps from like 1.3 to 1.4, so i dont know my exact voltage. So, is there a way to calculate what voltage my core is getting by having the ohm? Thanks in advance!

No, I don't think there is an easy way to calculate that. Use your multimeter and measure the voltage at the locations circled in green in the attached picture. It's a little hard to see with the molex in the way, but you should be able to figure out the location.

 

[BraveSoul]

What is your voltage BraveSoul?

currently 2.08-2.09mem 2.26gpu on load. idle is 2.10mem wierd... pencil mod is tricky. some games freeze..so now trying to lower clocks and stability/longivity test btw did some testing guys, posted benchmark scores of different speeds
click to check it out let me know what u think....810/1850 seems to hang on few games... testin current speeds

 

[[I.R.A]_FBi]

How does a stock 4850 cooler do with 1.2 V?

 

[cp#]

How are you all doing stability testing?

 

[BraveSoul]

How does a stock 4850 cooler do with 1.2 V?

hmm it will probably run even hotter, hey now it will heat up your room even faster
i dont recommend it

 

[BraveSoul]

How are you all doing stability testing?

very easy, FurMark for instance,u can use it as a benchmark,, and it has a stability test option,check windowed mod, lunch GPU-Z and watch your temps go up.u can dl it at
guru3d.com but im sure most ppl enjoy testing their system by playing their favorite game, for a looooong time hope this helps

 

[Scrizz]

How does a stock 4850 cooler do with 1.2 V?

It works fine as long as you change the fan speeds in RBE