Originally Posted by babgvant
The problem is that it varies b/w their dGPU - higher end cards do much, much better where a Zacate is pretty bad - something that might be correctable if they offered the option.
Good to know. I was considering buying some kind of passively cooled ATI card or new trinity APU hoping they offered similar a/v sync accuracy. Too bad it's not universal across all their new GPU's. Guess I got lucky with this crappy Dell OEM ATI card - they go for about $60 on ebay.
Originally Posted by jmpage2
Anandtech did some testing and I believe that the ATI 6450 is the most accurate GPU they had tested as of a year or so ago.
The 7570 I tested is a relabeled 6570 so maybe it offers similar clock performance to the 6450.
What people need to consider, and this may not be obvious from reviews, is that absolute 23.9760 perfection is not really the goal.
First, the refresh rate reported in programs like MadVR, MPC-HC, etc. is only as accurate as the PC timer used to time it. Try disconnecting your PC from external internet time synchronization and see how far it drifts in just a few days. So just because you see 23.9760 reported on your screen does not mean that's actually what you're getting.
Second, the sampling rate of your audio card may be slightly off from the ideal 48000 samples/sec as well. So it's entirely possible that 23.973 could give you fewer drops than 23.9760. This is why I only look at audio/video clock drift over time as opposed to absolute video refresh rate.
To prove the point, my Nvidia cards with custom resolution tweaking would report near perfect 59.9400 out to many more decimal spaces than the ATI card which reported 59.9388. Yet in practice, the ATI card a/v clocks stayed in sync much longer than the Nvidia on 59.940 content - probably because their HDMI audio clock was also slightly slower to better match 59.9388 video refresh.
I wonder what the "enforce smooth video playback" option in the ATI control panel does? The help just says "Enable this to ensure smooth video playback with no dropped frames". Why would anyone turn this off unless if has some side effects?