Overclocking an 8600m-GT: results and analysis

[lozanogo]

Well, this is my first thread.

I was motivated to bring in this brief report because: (1) I am intrigued by how good can be the overclocking performance, and (2) there is an amazing lack of information regarding overclocking results VS stock clocks.

The programs I have used are:
A) For overclocking (OC) and stability:
-RivaTuner: for overclocking.
-AtiTool: for stability measurement.

B) For benchmarking:
-3DMar06: standard benchmark.
-Half Life 2: Lost Coast (HL2:LC): A semi-old engine but very popular. I used its in-built Video Stress Test.
-World in Conflict (WiC): A modern game taxiing both the CPU and GPU. I used its in-built Benchmark.


TESTING ENVIRONMENT:
My specs are on my signature. My 8600m-GT is DDR2, so the stock clocks are 475/400 core/memory. All measurements were done at a resolution of 1280x800. I am using the 174.12 driver. All measurements were done under the same normal life conditions (always the antivirus (AVG) on and a couple of webpages open).

METHODOLOGY:
I increased by 15 MHz the core clock, then run AtiTool for artifacts for 10 minutes, if no artifact then I increased 15MHz the memory clock and run the AtiTool for artifacts for 10 minutes. I kept repeating until I reached the levels I wanted to benchmark: 10%, 20%, and 30% above the stock clocks. Once on those levels I run the AtiTool for 1 hours looking for artifacts, after that I run the three benchmark programs. The games (HL2:LC and WiC) benchmarks were run at least three times to ensure consistency of the results.

RESULTS:
I was able to overclock 10% (525/440), 20% (571/481) but not 30%. The maximum stable clocks were ~28%/31% clocks (609/525), and also I tried a little lower clock: 609/505 (~28%/26%). AtiTool was stable for more than 1 hour in the four overclocked settings. The temperature increase was from 69°C (no OC) up to 73°C for the maximum OC.

The following table summarizes the results:
__Overclocking _________3DMark06_____HL2:LC________WiC
__(core/memory)____________________(avg FPS)__(min/avg/max FPS)
A) 475/400 (+0%/0%)_____3543_________65.79 _____12/22/39

B) 525/440 (+10%/10%)___3871_________72.8_______13/24/42

C) 571/481 (+20%/20%)___4177_________77.86______13/26/46

D) 609/505 (+28%/26%)___4354_________82.26______13/26/47

E) 609/525 (+28%/31%) ___4455_________84.56______13/26/49


ANALYSIS:
The 3DMark06 benchmark show increases of 9.25%, 17.89%, 22.89% and 25.74% VS the 10%, 20%, ~27% and ~29.5% OC.

HL2:LC frames per second (FPS) increases are more close to the GPU OC: 10.66%, 18.35%, 25.03% and 28.53%.

WiC is a different story. The 10% OC gives about 10% increase in the FPS. The 20% OC gives another 10% only to the average and maximum FPS. Further OC's (~ 27% and ~29%) gave only a meager 2% and 6% increase only in the maximum FPS. At this moment my speculation is that since this game is both CPU and GPU taxiing, then there is a limit the effective GPU OC, 20% in this case.


CONCLUSIONS:
First of all, regarding the 8600m-GT: I was impressed by its OC capability. I knew 10% could be achieved, 20% was reasonable, but be able to go past 25% is already a great achievement. I know there are reports of 8600m-GT OC'ed at almost 40%, but I am not sure how long they can remain stable.

Second, I learned that OC'ing results from different games (or engines, to be more general) cannot be used as proof of the general increased performance, not even 3DMark06. Look at HL2:LC and WiC, while the first can follow the OC (no heavy CPU load), WiC can only increase effectively up to 20% on its average value.

Finally, the big question: is overcloking really worthy? I think I have no clear answer. Always the dilemma goes in those lines: can the performance increase really reflect something in the games? (in other words: are the extra FPS really seen/felt by the user?)
- From my results it is very palatable to see a continuous increase in HL2:LC, but I doubt I will see an increase from 65 to 84 FPS.
- On the other hand, a 20% OC for WiC is much better. I know (using FRAPS) that the real average during real mission lies in the middle of the average and maximum values of the benchmark, while the real minimum is like 5-6 FPS less than the average from the benchmark. Therefore, the effective 20% increase will ensure I will not go below 20 FPS and thus will not experience any kind of lag in the game.



Please feel free to comment or ask questions on this brief report. If you have found something interesting about overclocking, please share it with the community, so we can learn together from our personal experiences/experiments.

[Tinderbox (UK)]

Hi.

nice work, will come in handy overclocking my GDDR2

regards

John.

[dtwn]

Good job. +rep. I'm not completely sure if such comparisons haven't already been done previously though.

[Nokia 3650]

I love this analysis that you did. I'll definitely be doing this for my new notebook that I should be getting (in the next 3 days).
http://www.newegg.com/Product/Produc...m=N82E16834115
With your analysis, I know exactly where to start overclocking from (safely). I think I'll make the new clock speeds permanent (by flashing the GPU's BIOS).


What I now want, is a tool to enable me to overclock my 1.66GHz Core2Duo processor.

[Tinderbox (UK)]

Hi.

I thought we were only up to 174.31, but you say you are using 176.12

Is this a mistake, if not give us a link to it.

thanks

John.

[lozanogo]

Hi.

I thought we were only up to 174.31, but you say you are using 176.12

Is this a mistake, if not give us a link to it.

thanks

John.

Upppss, thanks for the info. I'll edit. Its the 174.12!!!

[HTWingNut]

Thanks for the analysis. Problem is that the WiC benchmark isn't really 100% representative of in-game performance. I find the game in general has siginificantly better performance than what the benchmark shows.

[lozanogo]

Thanks for the analysis. Problem is that the WiC benchmark isn't really 100% representative of in-game performance. I find the game in general has siginificantly better performance than what the benchmark shows.

Precisely, like I mentioned in the conclusions. Actually the benchmark used is with many special effects and zoom in into the action, therefore the benchmark is really for the most stressful parts of the game (like when having 5 or 6 air attacks and in zoom in).

[swoley2k]

I think this will be very useful for others. Good job. Can you put up your system specs and OS also? Thanks

[lozanogo]

I think this will be very useful for others. Good job. Can you put up your system specs and OS also? Thanks

I really hope these can help other people. My system specs and OS are on my signature.