8800m SLI, Volt Modded, running at stable @ over 700core/1000mem

DISCLAIMER!!! - I will not be responsible for what you do with your cards. However, I wanted to create a thread that would show those that want to play what the 8800m GTXs are capable of.

Before we get started. Let me explain the theory and the reasoning behind this whole thing.

Dell is not in the business of creating computers that burn up, and as most are very aware, they factor in a lot of room for overclocking and game enthusiasts that want to push their hardware to the limit. Here however, they did a "no no" IMO. However it's also the only way that they could tame the beast the 8800 is.

At the heart of the problem is the Dell PSU which is only rated at 230 watts and is close to being maxed and general heat generated by the cards themselves.

The standard 8800s as they arrive from dell, are set to run @ 1.00 volts. This however is a long shot from desktop versions of the cards running @ over 1.3 volts which are near identical in architecture. (some desktop users volt their's to over 1.4 volts!!!!)

What gives? Well from doing a little research, I found out that Dell, is not alone in undervolting these cards and Clevo along with dell does this as well except they undervolt even more! Down to 0.95V!!

Now the benefit of the undervolt, is that you generate a lot less heat. However the less voltage you allow the card, the less stable the card becomes at higher clock frequencies. From reading the posts on this forum alone, I noticed that most people run into artifacting between 620mhz and 645mhz core clocks and 950 memory clocks. The reason for this, is that at those clocks, you are asking the GPUs to do more work, then the voltage supplied to them will allow. All cards are different, but for the most part will run into stability problems before they run into heat problems. Testing this, I found that the GPU fans don't even kick on high during Crysis a game that should push any GPU and its fans to high.

From this, I knew that the GPU had to have more in it, then Dell and other laptop manufacturer would suggest. It wasn't long that I figured out I was correct.

What you need to do: READ THE WHOLE THING BEFORE TRYING ANYTHING!!!!!

Create a folder to work with such as “gpuOCfiles”.

Download: GPUz 2.3 or newer and read both your stock BIOS' and save as .bin files remembering to name them so that you can differentiate each between card 1 and card 2 (the bios versions for each card will end in xx.01 and xx.02 respectively for card 1 and 2 . To read and save each BIOS, you simply click on the “chip” icon next to the BIOS version. Do this for each card, selecting the next card via the drop down box in GPUz.

Download: NiBiTor v4.1 or newer and drag and drop each of the bin files into NiBiTor saving each one as a .ROM file again naming them appropriately for card 1 and 2. THIS IS YOUR BACKUP!

Now open up each BIOS, in NiBiTor. Go to the voltages tab. There, you will find, that you are unable to set the “EXTRA” voltage beyond 1.0v and you will find that there are some unknown vids. It's possible, that those are the voltages you need, but DO NOT USE THEM unless you are willing to gamble. Do this instead.

I found a guy, on a forum, (can't find it now) who changed the VID EXTRA values, so that they would be selectable in NiBiTor. I have them. You will have to PM me, and or FIND SOMEBODY TO HOST THESE! I have the BIOS' for 1.00v (stock), 1.05v, 1.10, and 1.15.

Once you have the modified BIOS'...

Download NV flash 5.63 or newer. Create a windows boot disk with CD-ROM support. (You can use other media if you want but I can only vouch for what I did). Go to http://www.allbootdisks.com/download/iso.html and download the win98_bootdisk.iso
open the iso, and add Nvflash and both (or more) desired BIOS' versions to the ROOT folder of the disk, so that you don't have to use “CD” commands in DOS. (WHY? I found NV Flash sometimes has problems reading the roms in non root folders.) Remember to keep you files labeled RIGHT! I don't know what result would come from burning card 1 with the BIOS for card 2 so just AVOID it! Also, make sure, that the file names don't contain “.,.” because NV Flash doesn't like it. Could also be a dos thing. Just name them something like “105C01.rom” for 1.05 volts Card #1 etc.

NOW PAY ATTENTION!!!!!! THIS IS IMPORTANT!!!! THIS IS IMPORTANT!!!

Reboot and at the prompt enter D:\ or whatever is your CD Rom drive or media. Enter “dir” to make sure that nvflash and the desired BIOS versions are in the root folder.

Now onto the flashing. READ THIS!!!!

AT THE CONFIRMATION PROMPT!! MAKE SURE!!! That the BIOS version you are FLASHING with is IDENTICAL to the one on the card currently!!! After you enter the commands below, it will ask you Flash XXXXXXXX with XXXXXXXXX if the numbers don't match I do not recommend flashing! If they do, go on.

At D:\ enter

"nvflash -5 -6 -i0 card1bios.rom" (-i0 is the BIOS Flash command for Card 1)
"nvflash -5 -6 -i1 card2bios.rom" (-i1 is the BIOS Flash command for Card 2)

After each command, provided that the BIOS versions match answer yes to the prompt and repeat for card 2 again making sure that the versions match.

Once done here, reboot and pull the BIOS with GPUz as you did at the start to make your backup, and check to see that infact the correct "EXTRA" voltages are being used by both cards 1 and 2, and run your ATItool and whatever bench you want at your desired clock speed. Keep an eye on the temps, and remember that the higher the voltage the more room for overclocking but the higher the temps.

I DO NOT RECOMMEND SETTING YOU CLOCKS TO PERMANANTLY RUN AT OVERCLOCKED VALUES, and have my reset to stock by not entering my desired overclock values within the BIOS'. I just use the nvidia control panel.

I also have my CPU undervolted to let the PSU have more power for the GPUs to draw, but this may not be necessary and I do it mostly to keep from throttling as I have the X7900 and not the X9000 which runs cooler.

From my experience the memory is the bottleneck on our cards maxing out at around 1000 +- 50mhz. I run mine at 950.

The GPU on the other hand, will take a lot more then just 500, 600, or even 700, but heat will be an issue.

With the above, I'm hitting 14.5K in 3dMark06 in VISTA X64 and the CPU at just just 3.0ghz and am running my 8800s at 1.1volts @685/950 with absolutely no artifiacting or errors in ati tool or any benchmarks. During gaming and benching, my laptop runs propped up in the back, without any external cooling. My GPU runs max of 88C in ATItool, and runs at 84C in Crysis. Don't quote me on this, but the threshold for these cars I think is 104C, but I would not dare go above the low 90s. Something about water boiling at 100C that just doesn't make me want to try. With external cooling it's possible to run these cards at 750+, at 1.15V, but IMO that's impractical, as I travel, and don't want to bring a cooler with me. Maybe one of those small wedge coolers but that's for somebody else.

Anyway, hope this helps.

It depends on how well off you are...LOL but, I think I would.

I think you have to take into account, that these cores are capable of running at 700+ and IMO running at 685 (for example) in my case is no sweat for the cards.

The most important factor will be heat. Can you trust yourself to monitor the temps. Because currently, if you by accident but your laptop on your lap, or block a cooling vent, it won't be too bad of an issue.

With the volt mod, the heat generated increases and the potential for overheating goes up. Most likely, your card will simply go into limp mode, and revert back to normal upon reboot, but you never want to do that so monitoring and making sure that the temps stay low, is paramount IMO. Other then that! There are IMO no problems.

As for the benefit, it's hard to say. I will be honest with you, in games that don't require much of our 8800s, who cares! It's more then fast enough as is, but for games like Crysis, where the framerates are lower, and 1fps, can make or break the experiance, the performance increase from the OC+vmod is significant. I don't have any hard figures, but I play Crysis64 at 1920x1200 all options on high, (no custom cfgs) and it plays great compared to stock figures. I noticed that my CPU overclock does little regardless of where I have it set, but OCing the card from 500 to 685, gives it those extra fps in an intensive game like Crysis, that take the "crap why is the frame rate so low" question out of the gaming experiance. Everybody knows, that Crysis can be overwhelming for the sstem during combat and sertain scenes, and not having the game slow down to the point that you notice the FPS drop is great IMO. So for me, it's worth it.

If you don't play intensive games like Crysis, why bother. You have all the power you will need, but I like playing Crysis and that fairly significant boost, becomes that much more significant when you're trying to sweeze every last FPS out of a game.

I can truly say, that with the above, I can enjoy crysis and not have to think about FPS. I just play the game and not worry about it. Before it, it was a bit noticable.

I can't tell you if it's worth it for you. That's up to you.