On multiple monitor cards, the driver is configured to prevent a switch in memory speed (i.e. On single monitor cards, the memory clock switch is synchronized with the blanking of the video signal at the end of a frame (legacy from the CRT era). I do only run a single monitor from this card though.Īll cards using GDDR5 memory will "flicker" when the memory clock changes because of the time it takes to retrain the memory channel. I don't have the flickering problem at all, nor have I. The fact that the memory clock becomes locked at the OC'd value and no longer auto adjusts as needed was described as a bug on a couple forums I found while doing some research a while back. I couldn't tell if there was an intermediate step or not.Īpplying my OC to 900/1300 locked the memory clock at 1300, but the GPU clock starts at 400 and will scale up and down as required. They idle at 157/300, and by stressing things a bit on the desktop I was able to get them to briefly jump to 600/900. When not applying an OC in CCC (overdrive checkbox cleared), my memory and core clocks will jump around depending on load. If your memory clock truly never changes, then you should not have problems with 2D mode flickering when using multiple monitors, or do you? That is what caused the issue in my setup, and evidently on others as google proves. See if at any point your GPU memory clock changes. Open the sensor page and put the card under varying levels of stress on your desktop. It's also somewhat risky to mess with the BIOS for the small performance gain, but it is a performance gain nonetheless I suspect a lower core clock could be used in 2D mode, but 550 worked for me. You no longer need the AMD Overdrive enabled because all the clocks are now hardcoded. If you aren't sure what proper voltages are for your card, check the TechPowerUp BIOS database for your chip and download an Asus or other make overclocked BIOS and copy theirs.įlash it and reboot, and you're good to go. Make sure to set the voltages properly, see my screenshot for example. ROM file ready in case the settings are wrong and prevent you from getting back into Windows.Įdit the profile settings such that all memory clocks are equal to your highest overclock on the memory, and while you're there put your highest core overclock into profile slot #0. Have a CD/Flash Drive/Floppy Disk with a DOS boot, ATIFLASH and your. rom file and put that into a safe location. Follow their documentation to import your card's BIOS.įirst step: After importing your card's BIOS, save it to a. That means more power, more heat and potentially shorter life than at stock settings, so keep that in mind.ĭownload Radeon Bios Editor and WinFlash from TechPowerUp. In other words, this fix will run the memory at it's highest overclock at all times, and the core at the lowest speed where it can keep up with demanding 2D tasks on 2 monitors. I also took out all the downclocks to 300MHz core, since that only works on single monitors. What this means is that the 1200MHz memory clock is required in all profile settings if I ever want to use it in 3D, because once the 2D mode gets under heavy load, the card will switch to the profile that's used in 3D mode (profile slot #0). On my card, the highest overclock that works in 3D is 775/1200 up from 725/1000. The ugliest part of it all is that there is no separate 3D clock. The fix involves flashing the card's BIOS. During transitions involving the 900MHz memory speed, flicker occurred. In my case, the additional profile setting used had a memory speed setting of 900MHz, while every other setting is 1000MHz. That explains why there is no flicker when not overclocking: memory speed never changes. Further, when not overclocked, the settings it transitions between all have the same memory clock. When overclocking the card, for some reason it transitions between more of those 7 settings than when it is not overclocked. My card's BIOS profile has a total of 7 clock speed entries, each containing Core clock, Memory clock and Core voltage. While stressing the 2D mode and leaving GPU-Z sensors visible, I observed that the flickering occurs when the card changes the GPU Memory Clock speed. I don't know if this is fixed in the 68xx or 69xx series. I have read that this is an old ATI problem, and (at least) 5870's are affected the same way. Switch between fullscreen/window on the Flash video. My test case: Open Steam and go to the Store page, run a 1080p video on monitor 2, run a HD Flash video in Firefox on screen one. Enable cheats ue4.When using two monitors connected to a 5850 and overclocking the card, strong flickering can be observed during 2D tasks.
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