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How does Coolbits determine recommended O/C settings?

Last response: in Overclocking
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September 30, 2006 2:53:24 AM

Thanks for reading. Recently, I purchased two 7900GTs . Both are XFX make, the particular model is UDF7, and these are clocked at 470 MHz - only slightly higher than the reference 7900 board which is 450 MHz.

I received these two cards and tested them extensively, individually, in my machine. It was discovered that one of the cards consistently performed 1.00% better than the other, but of course this is not a meaningful discrepancy.

So I shipped off this better card (I'll call it card A) to a friend as a gift. He almost immediately used Coolbits and used its recommended settings for overclocking. What was the recommendation? 562 MHz with 802 memory.

I was pretty shocked at the magnitude of this recommendation!

Nonetheless he has had no trouble. He observes that even when playing Oblivion on max settings at 12x10 resolution, his card never rises above 55 C in temperature.

So now I am intrigued to try Coolbits on my machine (I have card B). I don't think I'll leap from 470 to 562 in a single bound as he has done, however, I'd like to know how Coolbits determines the recommended overclock settings. Because he and I have the same GPU exactly, will the recommended o/c settings be the same for card B as it was for card A? What exactly is the input which goes into Coolbits' decision making?

Thanks in advance for any kindness and explanations.
September 30, 2006 4:06:53 AM

I have found coolbits settings are arbitrary guesses, that I can take the same card, flash a different bios and get substantially higher stable o'c, that using coolbits again to test with the new bios, Coolbits sets it far higher. The difference of the new bios was only that I'd edited it (the same original bios) to reflect higher default clock speed. So apparently, coolbits does not actually consider the highest stable speed at all, it makes some kind of guess based on what the default speed was.

I can't say from this that everyone would reap the same gains, obviously it'd depend on how much o'c headroom a particular card had regardless of what coolbits tries to suggest, but it is very fishy that coolbits does this.
September 30, 2006 4:48:03 PM

For me and my pletora of cards coolbits has always kind of guessed the right memory speed, yet i can always cracnk it up a bit higher

as for gpu clock speed, well, in some cases from 400 coolbits recomends 420, yet i can take these cards to 570mhz so go figure...

i usually do use coolbits to finda medium oc, then i slowly speed it up, first memory, until it tells me it has failed (small ocs) then i trim it up while testing with 3dmarks 2005 canyon flight test, it has prooven to show artifacts quickly with overclocked mem, lower until no more artifacts, then onto gpu oc

for this i just continue rising, until it crashes, lol but i take not of the last working number then lower it a bit and use that

for th enext hours i slowly rise up, until i eventually crash again, and voila, i found the cards limit


been doing this for years, never fried a card


cheers
!