How to Overclock SLI cards?

[Toxcity]

I want to overclock my 2 6800XTs.

But can't. One of my cards have 512MB memory and the over has 256Mb...

So to get them to work I have to have the coolbits value in the reg set to 18.

Nvidia say they can get overclocking and get the cards to work together by using the value 1A. But that failed.

Is there any overclocking programs that I can use which don't change the Coolbits value.



So damn annoying seeing as the XTs are very good overclockers. :yumyum:

 

[JN]

Not sure if its still about, but Rivatuner used to be a good program for Nivida cards.

 

[Toxcity]

Rivatuners still about but it uses Coolbits...

Thanks for the quick reply btw. :worship:

 

[Nagaru]

Have you tried ATI Tool, know it doesn't sound like it would work, but I believe Nvidia support has been added to the beta.

 

[Toxcity]

ATI tool works but only on one card.. .

SO close! :yumyum:

 

[FragTek]

How bout through nTune? I suspect it uses the Coolbits method as well, but worth a shot because I'm not positive.

Check out PowerStrip while ur at it, might have some luck there.

 

[Ham]

If your really commited you could mod the bios' on the cards

 

[FragTek]

Wirelessly posted (LG Fusic: Opera/8.01 (J2ME/MIDP; Opera Mini/2.0.4719/1378; en; U; ssr))

If your really commited you could mod the bios' on the cards

that might actually be the best way to do it. put the same bios on both cards and then they will both clock together with coolbits.

 

[Pyr0]

doesn't RivaTuner offer low (hardware) level overclocking of the cards?

 

[Toxcity]

If your really commited you could mod the bios' on the cards

How do I do this? :yumyum:

Isn't it dodgy? But im up for it.. :wavey:

 

[Pyr0]

last time i tried it (with a 7800GT), it was with NiBitor to mod the BIOS and NVFlash (on a floppy disk) to write it back to the card

don't forget to back up the original bios's first tho

LOTS and lots of tips and resources here:

http://www.mvktech.net/

great site covering most of the aspects of flashing gfx cards, you should be able to find lots of different bios's for various cards and tools needed for modding/flashing

that might actually be the best way to do it. put the same bios on both cards and then they will both clock together with coolbits.

not sure if that will be possible since the cards have different ammounts of memory...

flashing them both to 256mb bios's *might* work, but if it were me, i think i'd prolly just change the gfx clocks

 

[Toxcity]

Im a bit nervous about flashing the Graphic Bios.

Seeing as im POOR and cant afford another card if I mess up.

Ill leave it unless anyone has a neat safe guide thingy.

Frag, your the best at this stuff I believe.. well from what I have seen anyhoo. :wavey:

 

[FarFarAway]

Well there's guides but if you can't afford another card then I would leave it tbh. No point messing around with stuff if you can't afford to

 

[llwyd]

Look Here

me and ham shoved that together ages ago, i believe since then they have improved the app to make it even easier

 

[Pyr0]

if the bios is incorrectly flashed, it usually just results in a blank screen, but the card still works.

if you back up the bios(s) first, they can always be flashed blindly from a floppy disk

i wrote a small guide on another forum regarding voltmodding the 7800gt bios, below is a small extract regarding the creation of a floppy and for blind flashing

<snip>

First you will need to make a backup of your bios just incase:

Create a bootable floppy disk and then copy nvflash.exe and cwsdpmi.exe to the same disk

Boot the computer from the floppy, and issue the command:

nvflash -b a:\oldbios.rom

This will extract a copy of your video card bios and put it onto the floppy disk as oldbios.rom

Before you continue, you should be aware of the risks involved

I cannot be held responsible for any mishaps you may have or damage you may cause to your card. Incorrect flashing of your card can render it inoperable, and leave you staring at a blank screen.

To minimise the risks, you should have an old spare pci graphics card and/or a floppy disk containing your original bios.

If anything should go wrong and you don't have a spare pci gfx card, then you can still do something known as a "blind flash"

To do a "blind flash" we add the following lines to the autoexec.bat file on the floppy disc containing your original backed up BIOS:

nvflash -r

nvflash -4 -5 -6 -A -y a:\oldbios.rom

This will flash the bios of the videocard without requiring any user input</snip>

[edit] oops, too slow, looks like Llwyd has you covered

 

[FarFarAway]

Look Here

me and ham shoved that together ages ago, i believe since then they have improved the app to make it even easier

How'd I miss that? Stickied and repped both of ya

 

[JN]

Damn me too

More reps and loving as compensation for me missing your efforts

 

[Ham]

Hehe, cheers guy.

I don't know wich version to Nbitor we used for that. But the one I have now you can read & save the bios while in windows. Very useful tool.

 

[llwyd]

Hehe, cheers guy.

I don't know wich version to Nbitor we used for that. But the one I have now you can read & save the bios while in windows. Very useful tool.

lol thankyou. yea the new version makes it really really easy. would still make the floppy disc the same as in the guide though as a backup. if something goes wrong (pretty unlikely, i used that tool many many times on three different cards) you can do it from the floppy

 

[Nagaru]

I just had a thought about this, what if you disabled SLI found the highest common overclock for the cards, and then re-enabled SLI?