7900gs Overclocking

[keelers]

Hello all,

Im new to this site, and im kinda new to overclocking graphics cards in general (but i have done some research) so ive got a few questions. Just got a gainward bliss 7900gs 256mb and have tried to overclock it a little using rivatuner. The default clocks are 500/700 and i can (only) get to 520/725 before it starts to fail the clock test. Im not so bothered about getting more but it would be nice, and ive heard that this OC is nothing compared to others. But i would like to know what the clock test tests?..... At those clocks (520/720) it fails the test maybe once every 20 tries.....is this normal and should i be worried about it?....The test has passed at qyuite a bit higher speeds but not consistently. (also ive never seen any artifacts at any speeds - and temp never exceeds 48)

Ive heard that it fails mainly due to lack of power (this right?), this could be true in my case as i got just a 460w arianet psu. Any help what exactly the clock test is, and whether i should be worried about it failing it sometimes would be usefull. Id also take suggestions on how to stop it from failing


btw my system is

mb - asrock AM2XLI-eSATA2
cpu - amd 64 X2 4200+
1 gb 4200+ ram
7900gs

and for the power situation - 460w arianet psu
plus i got only 1 x IDE hdd and 1 x optical drive

[notsobig]

I think these questions are too hardcore for poeple browsing this forum including myself. I think you'll get better responses from people if you post this same question at guru3d where people are more graphically minded BTW, welcome to the forums.

[oralpain]

The clock test should never fail. If it does, there is a problem somewhere and instability may be evident in some applications. As far as I can figure the clock test runs a few short loops of some demanding code and then checks it for errors.

Also, the max auto detect OC is very close to the max stable OC for the card, if you run it when the system is warm. I have virtually never seen an OC be stable in everything, if it is higher than the auto detect. I have also found that OCs divisible by the reference clock tend to be "islands of stability". Reference clock is usually 27Mhz on the 7900s.

From a PM I sent last week, my 7900GS running at 710/909:

My load voltages are as follows:

CPU - 1.65v (needed a lot more voltage for the last 150MHz or so, does 2.55GHz+ at stock volts, but it works with more)
Chipset - 1.71v
System Memory - 3.15v

GPU - 1.47v (1.2v stock)
GDDR3 - 2.25v (2v stock)

Pictures of the card through out my modding process - http://blameless.crankeye.org/Blameless/pics/7900GS/

I have since reduced clocks to 702/900 for total stability (auto detected). I am adding a more cooling to various VRMs and upping the memory votlage some more. I may also shoot for 1.54v on the GPU, but im not sure if that is such a great idea on off the shelf air cooling. 729/999 is my current goal.

A note on the fatality heatsink, I generally don't like LEDs and senseless flash, but the fatality version of this hsf spins at 800rpm higher (hence better cooling) and is nickel plated (ie no corrosion), so it is actually superior to the non fatality model.

[keelers]

Ah thats some overclock...I realy dont have the expertise (or money) to go fiddling around with custom coolers etc, but ive heard that people have managed some series clock speeds using the original cooler that comes with the gainward. Anyway if figured out that its my memory that doesnt like going any higher than 720 (core can quite happily stand 550) . This seems odd as most people say they can easily get 750 -800 with the standard cooling. Ah well its still a pretty good card considering its price.

Cheers for answering a few of my questions

[Max Tractor]

Disable the clock test in riva tuner, power user/overclocking global/disable clock test set the value to 1

Now bench and find the max clocks

[notsobig]

Ah thats some overclock...I realy dont have the expertise (or money) to go fiddling around with custom coolers etc, but ive heard that people have managed some series clock speeds using the original cooler that comes with the gainward. Anyway if figured out that its my memory that doesnt like going any higher than 720 (core can quite happily stand 550) . This seems odd as most people say they can easily get 750 -800 with the standard cooling. Ah well its still a pretty good card considering its price.

Cheers for answering a few of my questions

It could be your bios holding back your memory overclock. Have you tried flashing back to some older bios revisions?