I've had some performance issues in the recent past and now found the cause: My HD7870 xt does not boost when my i7 4790k's iGPU is enabled and always sits at it's 925MHz base clock under load. This also means that OC via Overdrive or Afterburner is not applied.
Power limit is set to +20% and the monitor is obviously connected to the HD7870xt.
I also checked for temperatue issues, but my GPUs temp just barely reaches above 60 °C while the VRM's are at about 70°C.
Disabling the i7s iGPU in BIOS fixes the problem. Even after re-enabling the iGPU the boost stays functional until I reboot the system once again.
I also have tried different drivers, including 17.1.1, but it did not help.
Somebody else has encountered this issue or knows how to fix it? The iGPU needs to stay enabled though.
CPU :i7 4790k
MB: AsRock Z97 Fatali1y Professional
RAM: 2x 8GB Crucial LP LV CL9
SSD; Cucial M500 240GB
GPU: VTX3D HD 7870 Black
PSU: Be Quiet E9 580W CM
OS: WIN 10 pro 64Bit