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-   -   Overclocking the 6800GT... (http://www.nvnews.net/vbulletin/showthread.php?t=103110)

TB303 11-25-07 03:16 PM

Overclocking the 6800GT...
 
Hi People,
I have a good old trusty XFX 6800GT that now barely "pulls" in modern games. So the time is now to OC it and hope for the best.
I replaced the old and faulty fan with an Accelero X1 - and now the card idles at 55c and reaches 65C at load while running (425/1050)!

Anythign higher than 425 - Core and I start seeing artefacts. However the low temps, suggest there could still be room for improvement. I'm wondering if the card is runnign out of juice and if I shoudl bump the voltage, it's currently 1.60 I can do 1.65 in my Mobo's (AV8-3rd eye) bios.

Another thing which may be affecting stability is the fact I OCed my CPU - an A64 +3000 @ 2475 - it results in the AGP bus running at 68Mhz, and I could potentially get it to 70Mhz

Please share your thoughts,

Many thanks,

DJB 11-27-07 11:44 PM

Re: Overclocking the 6800GT...
 
When you talk about bumping the voltage in your system's BIOS, that is not bumping the voltage that the video card core is using, it is setting the voltage for the AGP slot. To change it on the card, you need to mod the video card BIOS. 6800GT card were notorious for not liking higher voltages than stock, so that is likely not going to help you. You are really running a pretty good OC for a 6800GT at the moment and I doubt another 5 or 10 Mhz is going to do anything for you in modern games. You just need to run low resolution with no AA and only light AF to play modern games on that card. I must say thought that I certainly got alot of mileage out of mine, and there is still one in my wife's rig.

As far as bumping the AGP slot speed; well that is not really what is limiting you so I would leave it as you have it. Once you hit 83 you are going to start looking at instability issues. I always found 75 as a good stopping point.

DJB

HarpooN 11-28-07 05:37 AM

Re: Overclocking the 6800GT...
 
What he says.
Our 6800GT's are hardly capable of running latest games, so we have to lower res (1280*800 works for me), and of course no AA, and sacrifice some options to medium or even low.
Said that, your oc seems right, but my card mems seem to oc a little higher than yours.It's a XFX, too.I usually keep it at 385/1090, and get no artifacts.
I replaced the cooler with a Zalman CU -something

Bman212121 11-28-07 11:13 PM

Re: Overclocking the 6800GT...
 
If your using stock voltage on the card then 425 is a pretty good OC. I had to bump with the voltage on mine in order to break 400. I think you could probably get a little more out of that card if you flashed the bios with a slightly higher voltage.

I still have the exact same card using the NV5 on it (predecessor to the accerlo) I could get about 420 max myself. It would do 435 but running 3dmark03 it actually yielded lower scores so I backed it down to about 420.

Here is a guide on howto flash the bios for the card. http://www.mvktech.net/content/view/2069/37/

Default voltage on the card should be 1.3V, and I bumped mine up to 1.4V using NiBiTor. http://www.mvktech.net/component/opt...rent,category/

Depending upon the age of the card, you might already have the latest bios. Version: 5.40.02.15.03 I actually grabbed on from their site and changed the voltage and flashed it to my 6800GT without issues. If you load up nibitor you can read your current bios and then dump that one to make a change. If it's up to date it is best to just use what's already on the card since you know it's working. If not then you can get the newest one here. http://www.mvktech.net/component/opt...rent,category/

If you decide it's something you want to try, just give me a PM as I actually have the latest bios for an XFX 6800GT AGP card already changed on my thumb drive from when I flash my card. Just remember that flashing can be a risky business because if it fails the card won't work properly. If you have a PCI video card, you can enable your bios to boot from PCI first then AGP, so if your flash does fail you can boot up the computer with both cards in it and then flash back the old bios to your 6800GT. Always make a backup of what is on your card before you attempt something like this. You can use Nvflash http://www.mvktech.net/component/opt...rent,category/ to change the bios file, but make sure your doing it in DOS and not windows using a boot disk of some kind.

EDIT: One more thing, I want to say that if you have an older driver like a 92.XX and coolbits you can unlock the ability to change the voltage right in the drivers. This way you can test it first to see if it's even worth the hassle of flashing the video card with a new bios. I'm not really sure anymore though cause that was a long time ago.

jimmor 12-06-07 06:01 AM

Re: Overclocking the 6800GT...
 
Quote:

Originally Posted by TB303
Hi People,
I have a good old trusty XFX 6800GT that now barely "pulls" in modern games. So the time is now to OC it and hope for the best.
I replaced the old and faulty fan with an Accelero X1 - and now the card idles at 55c and reaches 65C at load while running (425/1050)!

Anythign higher than 425 - Core and I start seeing artefacts. However the low temps, suggest there could still be room for improvement. I'm wondering if the card is runnign out of juice and if I shoudl bump the voltage, it's currently 1.60 I can do 1.65 in my Mobo's (AV8-3rd eye) bios.

Another thing which may be affecting stability is the fact I OCed my CPU - an A64 +3000 @ 2475 - it results in the AGP bus running at 68Mhz, and I could potentially get it to 70Mhz

Please share your thoughts,

Many thanks,

Your overclock to 425/1050 is very good for a 6800gt !

Achieving higher will require both Vcore and Vmem to be increased. Vcore can be increased from 1.3v default up to either 1.4v or 1.5v via a simple bios mod using NiBiTor; whereas increasing Vmem unfortunately requires a hard mod on the card. And all of the information to do so is readily available in this and other forum's ---> just search/google for it ?

However, with the 6800gt it's not exactly Core Volts or Temperature that's your enemy, it's more usually the card's poorly designed and thus weak Core volts regulator that decides how far you can push things. And over the years many people have found that only increasing Vcore to 1.4v was enough to way overstress and prematurely kill their card's core volts regulator ---> worth keeping in mind if you decide to go this route ?

As for your mobo's current overclocked 70Mhz AGP bus, you should be able to safely run the bus up to around 80Mhz !


:)


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