Something to think about...
SourceThe issue is due to the recently implemented feature of Catalyst drivers called ULPS. It is a power-saving feature that completely shuts down any non-primary GPUs in CrossFire configurations when the video card is working in non-3D mode (e.g. at Windows Desktop). When any of the installed GPUs are shut down, sysinfo tools like EVEREST can still read out GPU registers and sensor readings from all GPUs. This is the nice part.
The not-so-nice part is that for unknown reason when any of the installed GPUs are shut down, reading GPU registers from those GPU(s) sometimes (but not in all cases) causes a system lockup (freeze). This happens with all sysinfo tools that handle multiple ATI GPUs.
Before implementing that feature AMD contacted us. They warned us about an upcoming feature and its impacts. I quote from their email: "your application may come to a halt once we release this feature". We replied and asked for assistance about avoiding any possible issues when they implement ULPS. We got no help back then.
Once AMD actually implemented ULPS in their Catalyst drivers, we contacted them again and asked for assistance once again. We got no response at all.
Since then we've desperately been trying to find a way to avoid the lockups. We've implemented 2 workarounds so far, and it works on some systems, but not all. We've contacted fellow sysinfo authors to find out if anyone could come up with any solutions, but it seems so far noone could solve it properly, not even using AMD's assistance/help. Quite frankly, it seems this feature (ULPS) is implemented in a not-so-fortunate way that causes nothing but headaches to software developers.
One possible workaround surfaced lately. AMD implemented a special interface (ADL) in their drivers to let 3rd party software read out GPU properties via video driver calls. It's a nice idea and a nice gesture from AMD, but the way they implemented that interface is once again not great. Using ADL it may be possible to avoid lockups, but ADL calls work so slow that they make it impossible for us to read special values like GPU temperatures and voltages with frequent dynamic update.
Once we could figure out a working fix, we'll post it into this topic, and all other topics related to the same issue. Thank you for your patience.
Meanwhile, you can disable ULPS feature by setting the value for any occurences of "EnableUlps" in your Registry to "0". However, by doing that your non-primary GPU(s) will be driven even when they're not utilized, hence causing a higher system power draw.
Regards,
Fiery
Lavalys Everest forum
... but i personally leave it enabled.
How to disable ULPS:
- Regedit > select HKEY_LOCAL_MACHINE - > SYSTEM
- Hit Ctrl+F (= find), type in
enableulps
and hit Enter - each instance you find (F3 for the next search), change the value from 1 to 0.
Do not touch EnableUlps_NA. - Reboot the PC for the changes to take effect.