This issue I have already reported for the beta of 12.4 before a month in that post "12.3 RC 8.95 - BSOD with multiple device - multiple context - multiple threads". The second disabled adapter (without monitor, no crossfire) does not increase the core - and memory clock under full OpenCL load.
(see screenshot GPU-Z). This slows done the complete program, because the first GPU have to wait for the second. With old drivers (11.11) and HD 6970 this does not appear. Now I want to use the HD7950/7970 and wait for the first stable MultiGPU OpenCL driver since release of the GPU. The inofficial beta 8.97 is also affected by this issue. I hope it would by solved for the next release. If there is solution with that I can increase the the clock speed with some lines of code I would see this also as a solution. Thanks in advance.