I'm looking for some advice on an issue I'm experiencing.
System is an Asus P8Z77-V LK mainboard with Ivy Bridge i3770 CPU and a Radeon HD7970 GPU.
Using just drivers from Windows Update I am able to get OpenCL working on 4 devices: The AMD CPU+GPU devices, Intel CPU device and Intel IGP device. Tools used to check OpenCL devices were clinfo.exe, GPU-Z, GPU Caps Viewer and LuxMark64.
- Install Windows 8 with HDMI display connected to IGP only and IGP as primary display in BIOS
- Disable Windows Update and automatic driver checks during the Windows install
- Install Intel MEI and Intel Graphics drivers from windows update
- Install Catalyst driver (atiumdag 126.96.36.199 (Catalyst 12.10))
- Install APP SDK 2.8
At this point I can use all 4 OpenCL devices. Performance for each single device is plausable (comparable to online benchmark scores, can observce the devices heating up when used).
However if I reboot, the Intel Ivy Bridge IGP becomes unavailable for OpenCL. I tried a system restore, reinstalling the drivers, using latest drivers but can't get it back.
And the reason I'm posting this *here* is that if, between installing Catalyst from windows update and rebooting, I disable service 'AMD External Events Utility', it all works fine with all OpenCL devices remaining functional.
It seems the connection to rebooting the PC is that this service is not started by the WU installation but is set to start automatically by it, so starts after the next reboot.
Is this a known issue? I'm sure I've seen other postings with similar issues but no resolution.
Can anyone shed some light on what the service in question is for?
I'd also like to know what the service may be doing which causes this behaviour. I'm assuming its some sort of switching of the primary adapter in windows independently of the BIOS setting, or some persistent reallocation of a resource that causes the IGP OpenCL to fail. Maybe there are some commands I can use to revert whatever it sets?
Regardless, it doesn't appear that I can gain a massive performance boost via using both GPUs together, but I thought this configuration would be useful for testing OpenCL code.