Finally, please note that Premiere Pro CC has support for multiple GPU configurations on export (only one is used during playback) so having more than one GPU will speed up your output times.
as long as your psu can handle the two cards, shouldn't hurt to try it.
Physically, I have both cards in my system now, but I don't see any performance increase, and it may be a tad slower. I'm going to process a smaller clip with one card and with both to see what the difference is.
So I was able to run some test and found out some quite interesting things! I was using about 3 min of 4K footage scaled to 1080p 25Mbps .H264 (Blu-Ray), with Lumetri color corrections and default transitions.
- With both cards installed, both were participating in the export of the video.
- The 7790 GPU-Z reported that the maximum GPU utilization was at 100% most of the time (>90% of reports at 1 report/sec.)
- The R9 285 GPU-Z reported the maximum GPU utilization was at a maximum around 60% around 40% of the time!
- When I removed the 7790 card, the GPU-Z stats of just the R9 285 card increased significantly 85% utilization around 70% of the time.
- The video was rendered in about 5:57sec. with both cards.
- With just the R9 285, the video was rendered in about 5:40.
- It appears the performance of the faster card was bound by the performance of the slowest card in the system.
So I have now removed the 7790 card and kept just the fastest R9 285.
thats good info, thanks for reporting back. thats too bad premiere wont make good use of both of em.
I have narrowed down why the performance is being adversely affected. When I process 1080p footage, it is faster with the two cards, but when I process 4K DCI footage, I get the slowdown. Maybe it's because the 7790 only has 1GB of Ram?
its usually recommended to have between 3-6gb of vram for 4k, so yeah, it might be the low memory crippling the 7790.