Planning to buy a new GPU, the HD7970 or the HD6990.
Why these two? Because a friend of me sells them for 300€.
I know the HD6990 is much better, and yes i know the HD7970 has 11.1,overclocks well, runs cooler...
But sound is no issue and even if you overclock the HD7970, the HD6990 is still fatser.
Only thing that stands me in the way, that ATI cards with dual GPU or CC sometimes get flickering and/or tearing screen in full screen mode.
I know most of the time it isn't, but dont want to take the risk.
So i want some advice who knows what i need to do about it, or shouldn't I take the risk and get the HD7970.
Well only you can make the call, so I'll present you with two different scenarios I usually consider:
1) Yes, the 6990 overall is more powerful and in the majority of benchmarks beats the 7970, however for new releases, you may not be able to use Crossfire and will be limited to the one GPU, which will be considerably weaker than the 7970 alone. A few may just outright refuse to work with Crossfire at all.
2 ) The 7970 does win in a few benchmarks, like Elder Scrolls V, so it's not a total lost. And it does overclock very well, so you'll get a considerable performance increase regardless. Unlike #1, you won't be limited to an issue if one were to arise--if you weren't able to use Crossfire. You'll always be able to run at full performance.
Now it also matters with regards to resolution as well. If you're running at higher than 1920x1080, the 6990 would be the way to go. Personally, I prefer to get 1 powerful card, and then pair it up later, vs a dual-GPU card (i.e. 6990, 590). I'm picky about quality, so I always want to eliminate the "what if I can't use that"
But if both of them are being sold at the same price I'd go for the 6990.
DirectX 11.1 also is a negligible upgrade, in my opinion. The only addition to it I saw that matters to people is an API level integration of Stereoscopic 3D, so it wouldn't be driver/product based only like it is now. Maybe someone else can add on it, but I would bet performance improvements would be minimal, or non-existent.
Just make sure your motherboard is Crossfire capable if you want to add a second 7970. For one 6990, the board doesn't have to be Crossfire capable. For a second 6990 (aka Quad-GPU), it will need to support crossfire.