2dfx wrote:Ahoy! So I decided to go for a graphical upgrade and ditched the GTX570 for a R9 290X. With the GTX, I was able to use CRU to get 120Hz stable with no dropped frames.
Now with the R9, the max stable OC I can get is 96Hz and anything over 100Hz is unstable.
Attached is the current stable CRU profile I'm using. Windows 8.1 with Catalyst 14.4 with the clockgen patch.
Ideas?
Use "Timing: Reduced" instead of "Timing: Automatic", and see what happens.
Failing that, try slowly decreasing the porch/sync numbers (and reduce total) until the screen blacks out, then back off a little. You will get higher Hz at the same dotclock.
(dotclock = number of pixels per second transmitted over the cable to monitor, and sync/porches are dummy non-displayed pixels originally used as a guard pause between scanlines / refreshes, for resetting the position of a CRT electron gun , but that's not used for LCD displays).
We need to reduce Vertical Total and reduce Horizontal Total, to get you higher refresh rates at lower dotclocks, to solve the problem. ToastyX CRU calculates timings differently than NVIDIA Custom Resolution. They can result in different overclocking limits...
These things can be quite finicky, if you write down all numbers from NVIDIA Custom Resolution (front porch, sync, back porch, total, active/resolution, for both horizontal/vertical) then you can manually enter all 10 numbers into ToastyX CRU -- and be able to get exactly the same overclock. However, if a single number is entered differently, it's possible to completely lose your 120Hz overclocking ability until the correct number is re-entered.