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GTX670 Overclocking - checking for stability

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Seltox

Registered
Joined
Jun 8, 2012
I recently picked up an Asus GeForce GTX670 DirectCU II and am in the middle of overclocking it.

This is the first time i've overclocked a video card, so it's taking me a while to sort things out. The Asus GPU Tweak software was pretty bad IMO, so i'm using EVGA PrecisionX. Right now i'm only looking at the clock speed - haven't touched memory yet.

My offset is +190Mhz, giving: 1105Mhz GPU clock, 1170MHz Boost clock, and at load, with the 'Kepler boost', it sits at 1300MHz exactly.

Because this is my first time OC'ing a GPU, i'm not entirely sure what I need to look for with stability. I've been running Unigine Heaven to check for stability while moving my speeds up. At these settings I ran Heaven for about a half hour straight. Peaked at 63 degrees celcius, and the GPU clock speed stayed completely consistent at 1300Mhz.

The problem is, I was reading around and some people say that if the GPU Clock speed doesn't remain completely consistent during a test, that your overclock isn't stable - and this happens during a 3DMark 11 run. The GPU clock moves up and down a bit. It doesn't crash or anything, and seems to run fine.. But i'm still not sure about it.


Here's a screenshot to demonstrate what I mean by consistent while running Heaven
stablegpuclock.png


And what it does during 3DMark (I don't mean the obvious drops between the tests, but how the top of the graph is 'ragged', not sitting at 1300MHz):
3dmarkh.png


What are the best guidelines to follow for checking stability with a video card?
 
As I understand it the 6-series nvidia cards have basically a turbo boost feature which makes overclocking less consistent with the same speed. I'd say if you passing the benchmarks at your set speeds out is stable
 
The reason why it keeps changing speed is the boost multiplier is determined also by temperature. I think the maximum boost is used whilst the card is under ~70C, then it will drop one multiplier until it cools down again. Or if it keeps getting hotter, the multiplier will keep dropping every few degrees. If you aren't getting crashes then I think you are good.
 
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