Settings: Overclocking
Use Device
Here you can select another video card on which ATITool will work, if you have multiple ATI cards.
The list below the drop down shows miscellaneous information about your video card.
Apply clock immediately...
If you are tired of clicking “Apply” after moving the sliders, you can check this box. Every change you make is instantly applied. Be careful, if you slide with the mouse while changing the clocks you might crash your system in no time.
Lock reference divider
On ATI cards there are two clock speeds. One for core and one for memory. Synchronized clock speeds have been dropped a long time ago. Both clocks use a common clock source, refclk.
coreclk = Xcore * refclk / Ycore / refdiv memclk = Xmem * refclk / Ymem / refdiv
As you can see both formulas share the refclk and the refdiv.
The reference clock is a fixed value, but the reference divider can be changed. To be as close as possible to the desired clock speeds, ATITool varies the Reference Divider of the clock generation circuitry on the video card. The problem with that is, this has a small effect on the other frequency (Memory if you’re setting core, for example). While ATITool tries to minimize this effect, some users might want to disable this altogether - thats what this option is for.
Clock safety range
If you know your card can’t handle certain clock speeds, and you want to make sure you can’t accidentially set these clocks, enable this feature and enter the desired ranges.
Another use of this feature is if Find Max crashes at a certain frequency without detecting any artifacts. Set the range here again and Find Max will (hopefully) stop early enough, so that your card does not crash.