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Overclocking my 2x7900GTX SLi.....

jpe20

jpe20

jpe20

Associate
Joined
5 Jun 2006
Posts
155
Hi folks,

Now I have received my replacement gtx card I can now motor on and sort my gfx sub-system out. I have just setup my cards in SLi combo and run 3dMark06.

Score in 3dMark06 with stock speeds (650,1600) is 8596 which is the going score I think for a 2.5GHz(oc) 3800x2 cpu etc.

I have an ASUS board and have tried things like Linkboost and PEG mode set to Fast/Faster etc but found that this made no difference.

When running 3dMark06 my temperatures peaked at 72C which from reading around leaves me 20C or so to play with ... is this right????

My plan is to install the latest beta drivers 92.xx to update my current 91.43? drivers as people do seem to have had a small performance boost with these betas.

Then actually its the overclock itself. I want a stable 24/7 overclock and I would like to do one that will not put my cards at too much risk because at 300quid a piece I cannot afford to replace these easily. So its a modest overclock I am aiming for.

The cards are identical and are ASUS EN7900GTX 512MB cards.

Any tips and anything else I can try to boost my 3dMark06 score will be apreciated.

What are the best oc utils for 7900GTX cards. I have heard of rivatuner something called coolbits? etc

Jules
 
why do you want to over clock 2 x 7900GTX's??? Just for 3dmarks scores seems a bit daft! (IMHO)

Your X2 will be holding you back - your CPU will bottleneck the cards.
 
I am not overclocking just for 3dMark06 scores. I am just using it as a reference thats all. I just want to do a modest oc and then leave it alone.

The cpu is probably losing me 400-700 marks (compared to FX62) I suppose though I will probably buy a cheap 65nm AM2 chip later next year.

Anyway I'll try out these beta drivers first.

Jules
 
Disappointing that you only get 300 marks more than my 7800GT SLi setup. (3800+ x2 @ 2500MHz)

Ah well, at least you put my mind at rest that I can keep my cards until DX10 hardware hits the shelves :p
 
In SLI, do you other guys get the detect optimal frequencies button when you install coolbits?

I didnt when i had SLI 7600GT, and still dont now with my current cards.
 
jpe20 said:
paradigm .... is your 7800GT SLI setup overclocked???
Click to expand...

A little bit yes :)

MeatLoaf said:
In SLI, do you other guys get the detect optimal frequencies button when you install coolbits?

I didnt when i had SLI 7600GT, and still dont now with my current cards.
Click to expand...

I let it detect optimal yes, seems to be a nice simple way of getting them to be the same and stable.

Manually clocking them was a lot more effort for minimal gain.
 
I downloaded and installed the latest nvidia forceware beta 92.91. Guess what ... did not work!!!! For some strange reason I could not enable SLI and it seemed determined to run 1 card only. Even in the nvidia control panel the usual SLI option just was not there. I think I installed it correctly using Add/Remove programs to remove the display driver then driver cleaner to tidy up.

So I have simply reinstalled my old drivers 91.47 for now. Any ideas???

Anyhow I am going to give coolbits a go later.

Jules
 
jpe20 said:
The cards are identical and are ASUS EN7900GTX 512MB cards.

Any tips and anything else I can try to boost my 3dMark06 score will be apreciated.

What are the best oc utils for 7900GTX cards. I have heard of rivatuner something called coolbits? etc

Jules
Click to expand...


I had two ASUS GTX's both did 700/1800 24/7

The problem is your cpu,

It's just not fast enough.Remove this bottleneck and let your SLI rig shine.

2.5ghz is not really enough grunt on x2 3800

My single GTX on my old opteron 170 @ 2.8ghz finally showed its colours.

Of course conroe makes this bottleneck non existent.At 3.8ghz any card will show its full capabilities.
 
easyrider .... looks like your right, the cpu is definitely the bottleneck as I cannot seem to push the 3dMark06 score beyond 8652!!! This is even in an overclocked state (modest) at 680/1700. I do not want to push it too much as the cooling around the graphics cards is not ideal due to a TV card being in between my GTX cards and hence sort of interfering with airflow.

I am due to get a Titan Amanda in October so should be able to push the cpu up to around 2.7GHz at least I would imagine. Failing that I am getting a new 65nm AM2 when they come out next year.

Jules

PS I have not bothered switching off background services etc in order to improve things.

PPS I have installed the latest NGO 91.47 drivers instead which function and allow easy manual overclocking though did not give me any boost over normal drivers.

PPPS Linkboost seems to do nothing .... is this normal???

PPPPS is it worth me reading in depth the nvidia 590 chipset overclocking guide?? Or will it be a waste of time anyway and it will be best boosting the cpu situation?
 
jpe20 said:
Jules

PS I have not bothered switching off background services etc in order to improve things.

PPS I have installed the latest NGO 91.47 drivers instead which function and allow easy manual overclocking though did not give me any boost over normal drivers.

PPPS Linkboost seems to do nothing .... is this normal???

PPPPS is it worth me reading in depth the nvidia 590 chipset overclocking guide?? Or will it be a waste of time anyway and it will be best boosting the cpu situation?
Click to expand...

Have you got the driver set to perfromance with AA and AF switched off?

Try the 92 betas they are nice.

Try clocking up your cpu find its max with around 1.55v.
 
easyrider .... I have already set to performance with AA and AF off. Also I have tried the new 92.91 betas which strangly would not let me enable SLI!!!!!

So I am stuck for now. Unless any1 has any other ideas that are worth trying I think I shall wait for my new cooler to come through in early october.

I have managed to clock up to 2.7GHz on stock but the system was not Prime95 stable nor could boot. Also the temps were wild!!!! Even @2.5GHz I am hovering around 60C which is hot though that is under dual core load with 2xcore Prime95 small fft.
 
Just played a 20min session on the GTR2 demo and boy was the gfx card hot!!! Is it normal for the heatpipes on the cooler being too hot to touch??? 1-2mins later I ran smart doctor (asus util) to see what the temp was and it was a whopping 78C!!! So what it must have been during gameplay!!!! Is there a good way of monitoring gfx card temps while you are running a game???

Jules
 
The GTR2 demo froze on me ie the game just stopped like pressing pause on a dvd etc. The computer was locked up "ctrl alt tab" no go and soft reset no go. Needed to power off the system and restart. I assume this is a graphics card overheat/overload symptom??????? This happened 15-20mins into the game. I am sure it is not the cpu as it has been tested Prime95 stable on both cores for 24+ hrs.

Anyway I have pulled back the overclock 10MHz on gpu core and 25MHz on the memory. Seems to be more stable though I have not yet had a long gaming session ie 30mins+.
 
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