The main advantages of HD 7750 over GT 640 I found are:
- Working full / limited range RGB levels (NVIDIA requires a custom resolution or a registry hack)
- The ready-for-use 23Hz refresh rate closer to 23.976Hz as well as 24Hz (NVIDIA requires a custom resolution; then it loses 24Hz, not good for European users; for stereoscipic 3D, we have to switch back and forth between 2D mode and 3D mode manually to make use of 2D custom resolutions.)
- Support for 88.2kHz/176.4kHz LPCM over HDMI (NVIDIA can't output these sample rates in WASAPI exclusive mode, not good for music lovers)
- No dual audio stream (yet); not good for 3D with a HDMI 1.3 AVR. Actually this does not matter at all if you use SNB/IVB (use Intel iGPU for audio)
- Two HW accelerated decoders (DXVA2CB, QuickSync) vs three (CUVID, DXVA2CB, QuickSync) under madVR (and Intel processor)
- No support for 4K decode yet. Well, this does not matter at all, IMO (simply because there is almost no 4K content nor affordable 4K display yet); NVIDIA can't decode 4Kp60 either (maybe GDDR5 fixes it?).
The advantages weigh more than the disadvantages for me (the disadvantages are actually not true disadvantages), that's why I prefer HD 7750.
Edited by renethx - 6/27/12 at 10:46am