3D Graphics - Complex test

[Sheena]

I get weird results in this test. See..

My system :

Core 2 Duo E8400
4GB DDR2-1066
GTS 250 1GB

1st run : Gpu stock (738/1836/1100) -> 86.7

2nd run : Gpu overclocked (771/1912/1150) -> 82.1

3rd run : Gpu UNDERCLOCKED (675/1688/1002) -> 99.4

Any idea what's going on ? lol

Edit: I undercloked as far as evga precision let me (570/1424/825) and i get 95.8. That's awesome i manage to beat some GTX 260's score with a GTS 250 undercloked by 30%...

[David (PassMark)]

Maybe it overheats when overclocked and throttles performance. Or maybe there is some random variation from one run to the next. Did you try multiple runs at the same clock speed? Or maybe evga precision is all that precise in what it is reporting?

[Sheena]

Yea i tested several times to be sure and it's really consistent. More i underclock better is the fps. When i test with my "overclocked" settings (around 5%) my gpu never go above 50C so we can eliminate a possible overheating problem. My gpu is never too hot anyway since i have a huge Zalman cooler on it (highest temp i've seen was 62C in Furmark).

I still tested with a more extreme overclock

GPU overclocked by ~10% (805/2014/1250) - > 76.2 fps

GPU underclocked by ~ 30% (570/1424/825) -> 96.1 fps

GPU stock (738/1836/1100) -> 87.3 fps

I don't get it because when i overclock in real games i obviously get better framerate.

Edit : Before you ask my PSU is Corsair TX 750w (60a on 12v rails)

[David (PassMark)]

Do you see the same behaviour on the DirectX10 3D test?

I wonder if the complex test is CPU bound on your system. And slowing the GPU actually allows the CPU to run faster (for some non immediately obvious reason).

What does the CPU % load look like during the tests.

[Sheena]

The CPU load is about the same (core 0 at 90-95% and core 1 at 5-10%) but i noticed the benchmark run fine only when the graphics card load is 100% (when underclocked). With the GPU at stock speed or overclocked the GPU usage is around 80-90% and the benchmark stutter slightly. Unfortunatly i can't test dx10 because i'm still using WinXP.

I overclocked my E8400 to 4.05ghz and i still need to underclock the GPU to get better results.