Video card overclocking...

[Cobra]

I have run into a very interesting problem when trying to overclock my month-old FX5900. I wondered what everyone else thinks the problem might have been.

I have an Asus FX5900 - nice, big copper heatsink over the GPU and aluminium heatsinks over the RAM. No cooling problems there, although I don't have any means to measure the temperature.

I put CoolBits into the registry to allow driver-based overclocking, and used AquaMark 3 as a test for the settings. I started ramping up the GPU frequency first. I got it from 400MHz to 451MHz stable. All was well. Then, I ramped the RAM up from 702MHz to 750MHz. Suddenly, AquaMark (and all other games) suffered a huge 2D and 3D performance drop. I lost 68% framerates on average.

My first thought was thermal throttling - the GPU must be getting too hot and backing itself off. I shut down and waited ten minutes for everything to cool off. I used a very sensitive probe to tell when it was ready (my finger). So, I booted up and experienced the same trouble.

I then took all overclocking off and rebooted as standard. Still, massive drop in framerates.

I deleted CoolBits out of the registry and rebooted. Everything was back to normal. How bizarre.

I can see that touching the memory settings in CoolBits caused a large deterioration in video performance. What I would like to know is why. I can still overclock the GPU no problem, and I am sure I can overclock the RAM using a video-specific overclocking utility.

Anyone got any ideas or theories on CoolBits causing this?

Cobra

[BrainStorm69]

It seems unlikely the coolbits hack would be causing the problem. I'd almost be willing to bet that you've oc'd your gpu too high. It's been quite some time since I messed around with going for a max video card oc, but if memory serves me correct, oc'ing the memory too much usually causes video corruption, not massive frame loss.

However, if you are sure you set everything back to normal and still had problems until you deleted the coolbits hack, then that is strange indeed.

I'd redo the hack and try again just upping the memory first. If you still have problems, delete the hack again and try using RivaTuner instead and see if that works. If so, then maybe Coolbits is causing your problem.

****EDIT****

The only other thing I can think of is that Asus almost never follows the nVidia reference designs (at least they haven't in the past), and perhaps that might be a reason coolbits doesn't work right on your card.

[Cobra]

Hi BrainStorm,

It is the CoolBits registry tweak. It works fine for GPU overclocking, but as soon as the memory is tweaked it brings it all crashing down. As soon as CoolBits is off, all returns to normal. When I change it back to "No Overclocking" and leave CoolBits on, it makes no difference.

I didn't know that Asus like to be different, so that could be the root cause. I tried RivaTuner too, but it also failed when I asked it to overclock the memory.

Thanks for your reply! Any other ideas?

Cobra

[BrainStorm69]

Here is perhaps a pertainent thread..although perhaps disturbing...it may be a hardware failure.

http://www.bleedinedge.com/forum/showthread.php?t=5224

On the other hand, it appears many are having problems with the new nVidia 6x.xx drivers. What drivers are you using? See thread below, hope it helps.

http://www.nvplanet.com/forums/index.php?showtopic=2268&st=0

[mujahid7ia]

Hi BrainStorm,

It is the CoolBits registry tweak. It works fine for GPU overclocking, but as soon as the memory is tweaked it brings it all crashing down. As soon as CoolBits is off, all returns to normal. When I change it back to "No Overclocking" and leave CoolBits on, it makes no difference.

I didn't know that Asus like to be different, so that could be the root cause. I tried RivaTuner too, but it also failed when I asked it to overclock the memory.

Thanks for your reply! Any other ideas?

Cobra

I don't think Coolbits is the problem, because, as you said, w/ Rivatuner Mem OC'ing also caused problems...

702 to 750... I think that is taking it too high and too fast. Try 5 or 10 mHZ at a time, and see what's stable and gives performance increases.

Aquamark3 is pretty intensive on the VRAM, because it has high polygon/texture counts in many tests.

[Cobra]

I have tried ramping it up slowly, but as soon as I touch the RAM settings the video card loses it.

EDIT:

BrainStorm69 - You were spot on! Thank you for the links! I took my driver back to 56.72, and my card is now fine with memory overclocking. I will investigate this further when I have some more time, and let everyone know. Thanks again!

[mujahid7ia]

Wow. Maybe I should I go back to the 52.72s also, because I've been dabbling in some GPU and VRAM OC'ing myself...

[Cobra]

I have achieved 446MHz (from 400Mhz) GPU and 818MHz (from 702MHz) VRAM speeds, stable. Seemingly, the newer drivers don't affect GPU overclocking - only memory. A 1MHz raise results in the loss of 2/3 of the graphics power.

Maybe nVidia were getting tired of overclockers hijacking the ample headroom they built into their kit.

[mujahid7ia]

I have achieved 446MHz (from 400Mhz) GPU and 818MHz (from 702MHz) VRAM speeds, stable. Seemingly, the newer drivers don't affect GPU overclocking - only memory. A 1MHz raise results in the loss of 2/3 of the graphics power.

Maybe nVidia were getting tired of overclockers hijacking the ample headroom they built into their kit.

LOL
or they wanted you to think your card was slow, so you'll get a 6800 Ultra Extreme Super Duper Supreme OC Edition (or w/e the best version is).