“I could get used gtx660 or gtx660ti around 60€. Is there any big changes between architectures/support?”
For MainConcept AVC CUDA support you need a Fermi Architecture card like Geforce GTX 5xx !
The Kepler Architecture Geforce GTX 6xx card don’t work very well.
Here’s a test I made in Sony Vegas Pro 12 (Build 563) 64bit – Have used 9 pcs. MP4 H.264 (.mts) 24Mbits recordings – total length 1:00 min.
MainConcept AVC template only cpu rendering:
GTX 660 : 01:55
GTX 580 : 01:48
MainConcept AVC template CUDA rendering:
GTX 660 : 01:49
GTX 580 : 00:29
The GeForce GTX 560Ti – is a good old card for Vegas Pro !