OCing question

Hey, I have a question about OCing. At stock memory clock of 800MHz in GPU-Z under the sensors tab it shows my memory clock as 799.9MHz. I overclocked to 900 in afterburner and in GPU-Z it displays the memory clock as 899.4MHz. Is the difference between set clock and actual clock normal?. My card is 6570m, which is nearly the same as a 5730m. I know the 5730m was/is a very popular card in laptops, so has anyone else had the same experience OCing a 5730. I bumped the core clock to 750 and mem to 950 (948.4) and within 15 mins of testing for artifacts in ATITOOL artifacts appeared. Is the strange actual mem clock of 948.4 to blame? Or is that just the limit of my card. At 750/900 my card is stable but at 750/950 it is not.

 

It's just the limit of your card's memory. Stick with 750/900. The "strange" clock is just what it runs at, it gets as close to your specified value without going over. My 5830 does the same thing with having "inexact" clocks. If you look at the tool, it even does that when you're not overclocking.

 

Thanks for the answer (+rep). I would have liked to have been able to OC more. I did go 50 higher for my core clock to 800. I get 9951 in 3dmark06 now. I used to get about 8100. A near 20% improvement is nice. I tried going up to 1000 mem clock for about a minute and got very bad artifacting in ATITOOL. I guess I'm staying at 800/900 for now.

 

To understand this you need a little understanding about how clocks are generated.

The most commonly used timing source are timing crystals, these crystals under the right conditions will oscillate at a very precise frequency. This frequency can't be changed and is often something like 14.87mhz.

Now using multipliers and clever circuits you can get clock steps in 1mhz intervals. This can take space and is tricky to do, so you will find that jumps often happen at say 7mhz intervals (notice how thats half the common frequency, thats no coincidence) or larger because the circuits can be simplified where such fine control is not needed.

So while the overclocking program may show 1mhz changes, the real frequency will snap to the closest actual frequency it can produce.

 

Yeah. What he said