I am thinking that Apple is doing something special to make the graphic performance of hackintosh staying half. I don't have many cards to prove this. If you guys are interested, please post CUDA-Z screenshot compared to CUDA-Z in Windows.
CUDA-Z can be found here:
I thought I had built a perfect mackintosh, but I was wrong. The GPU kept running at half speed
I changed smbios from MacPro 3,1 to iMac 12,2, and I noticed that AppleGraphicsPowerManagement.kext was loaded, but the GPU was still running half speed no matter I kept AppleGraphicsPowerManagement.kext or had it removed.
Please see the pictures. Performance in Windows 7 is much higher than that in OS X.
gpu-win.jpg 41.41K 57 downloads
gpu-osx.jpg 106.24K 55 downloads
=== Software ===
OS X: Mountain Lion 10.8.3
Method:Un1beast + Mu1tibeast + DSDT
CPU Speedstep: Perfect
Sleep, Wakeup, Restart, Shutdown: Perfect
LAN, Audio: Perfect (Yes, even recording from mic)
=== Hardware ===
Pentium Dual Core E6300
Nanya 2GB DDR2-1066 *2
Gigabyte GeForce GT240 with 512MB GDDR5
WD 320G SATA HDD