I'd go for the GTX570, especially if you were previously satisfied with the GTX drivers with your motherboard and OS. I'm tempted to buy a GTX550Ti or GTX460 card (if I can find one in a really good sale) myself simply because of the issues I seem to run into with Catalyst drivers from card to card.
Not only does Passmark rate the GTX570 higher than the HD6970, it's rated a better value re: price/performance. While Passmark isn't the only benchmark/review site out there I like their methodology. Other sites too often seem to have more restrictive test platforms and methods which can bias testing which could or provide somewhat misleading results.
However, IF there is a specific game and/or platform that is close to your planned usage being provided by a different website that compares these two cards, you might find that more useful.
edit: got more specific with which GTX cards I'd try assuming a sufficiently low price
The 6970 is better but not by much. If you're that used to Nvidia cards then grab the GTX570, though If I were you I would get the better performer, wouldn't you want to try out an Ati card for once?
I still think past experience with reliability and stability remains a critical component in the purchasing decision. If one hasn't had much trouble with AMD/ATi cards on a specific system/OS, then go with that brand, depending on budget. Similarly for NVIDIA. I wouldn't sweat over published performance ratings that differ by about +/-10%.
I just can't see either the HD6970 or GTX570 being the undisputed "better performer". These kinds of tests and their results leave a LOT to be desired when it comes to scientific rigour. Just looking at the way they flipped back and forth depending on which game/settings Tom's used shows high variability due to just a few settings...never mind the variability that would be introduced in results from fundamental system and OS environment differences.
If you use the compare checkboxes on the 6970 and 570 to look at specific tests on Tom's, you'll see the 570 comes out "ahead" in some games and benchmarks (e.g. Mafia2, maximum settings), while the 6970 is "ahead" in others (e.g. Alien v Predator, maximum settings). But it's likely even minor system and system-state differences between tests could overwhelm the video card performance differences, perhaps even flip them. Use a different system or OS/patch level and you could get significantly different numbers. http://preview.tinyurl.com/4x3ob7a
(this takes you to a preview URL to a HD6970 v GTX570 comparison page on tomshardware.com Just click on the "proceed to this site" link if you feel comfortable doing so.)
Honestly it's my favorite card to date. I have no problems playing games on the highest settings, even Crysis 2. It easily unlocked to a 6970. I did have a problem in FEAR 3 with it crashing(but no other games), so I downclocked it a bit and no problems now(FEAR 3 is very touchy with overclocks, sadly). For the price, I think the 6950 is the best deal if you unlock it, otherwise the 560Ti.
oh, ya then that makes sense lol. I am a bit jealous of my friends 560ti that runs at half of my temps.
Though I was surprized, this was the first summer when I had my 800D, and even at full load during 35+ degree days my temps weren't high at all. This is all considering 2x470's that do run at 90 degrees, and absence of air con in my house.
First time ever didn't need to run my comp with the side taken off.
whats the point of going from 4xx to 5xx series of cards....
I'm not sure if you're limiting that to just NVIDIA 4xx to 5xx or meant to include AMD 4xxx to 5xxx as well, but some of the differences apply also to the sound handling features. For example I think that if you want lossless pass-through audio on the AMD cards, you have to be at least in the 5XXX series. It may be also dependent on specific manufacturer and/or model number within the series.
As for NVIDIA 4xx cards, that too may depend on specific manufacturer and/or model number within the series.
That would be an important consideration if you want Dolby TrueHD and DTS-HD Master Audio routed without modification to your audio system.
I don't know for sure because I don't have a sound system capable of either Dolby TrueHD or DTS-HD Master Audio...I'm still at the "old" 5.1 channel Dolby and DTS decoding. I don't see any need to go with more than what I have in my lounge and consider HD audio to be a marketing gimmick.