Nvidia Performance overclocking issue

[Lunait]

I'm having a problem with overclocking my GTX 295 using the Nvidia Performance utility in the control panel. I can adjust core, memory and shader frequencies individually, but it won't let me raise the core clock above 616 MHz. If I try, it just says "The changes made were invalid and will not be applied". I recently installed a watercooling block on it, if that's of any importance. What is the cause of this, and can anything be done about it?

[Lunait]

Nevermind, I figured it out - turns out core and shader frequencies are linked, so raising the shader clock will allow for a higher core clock.

[LedHed]

just a note 196.21 drivers had OCing broken and 196.34 fixed this issue

[BenchZowner]

Nevermind, I figured it out - turns out core and shader frequencies are linked, so raising the shader clock will allow for a higher core clock.

There's a 1:2 ratio [ GPU Core:Stream Processors ] ( minimum ) that you need to keep to be able to apply the clocks.
You can have higher SPs, but never lower than 2x the GPU Core clock.

The SPs are clocked in 54MHz steps.

[cearley]

can you mess up the vid card by clocking the shader freq too high? I am trying to run my 8800gt at 700 core, 1000 mem. I know it is stable there. At those settings what should my shader freq be?

[BenchZowner]

1450MHz.
But you can run it higher with no issues ( as long as it's stable ).

If you need help overclocking your card, here's a detailed guide (http://www.benchzone.com/page.php?al=geforce_overclocking_gui) ;)

[Lunait]

Thanks for the tips everyone. Currently at 754/1657/1230 MHz (core/shader/memory) and 3DMark Vantage runs fine. Tried a few games and they run nicely too. :) How far does this thing go? I don't think I'll get the core up to 800, although it would be nice... what do you reckon is a safe voltage? I'm at 1.2V now.