2 Radeon 5700s or one 7970?

Take out the 5700s and burn them. The 7970 is the single best GPU on the market at the moment. And no you cant use them all together.

^+1 Agreed!

Agreed
2 x 5700's wouldn't even keep up with a 6950.

+1 for a 7970

You lucky *beep*... Free $600 GPU. The best GPU on the market right now... -.- Yes it will kill quad fire 5770s.

Actually, quad fire will not beat the 7970. If 2x 6870 outperforms the 7970, how will 4 5770s not? Think about it.  

Btw, I know it was a hyperbole.  

7970 offers more performance for power.
has less idle and long idle power consumption due to improved power management e.g. powertune and zero core power. it will use less power in idle mode compared to 2x 5770.
since you got it for free (i am assuming), performance per dollar is unbeatable.
no microstuttering (if you're susceptible to that) and hassle with crossfire profiles and driver issues.
less card = less heat and more airflow.
7900 won't cfx with 5700. they belong to different underlying architecture and different number series. besides, amd will never allow a high end card cfx with a lower end card.
you get 3 gb vram for your gpu - good for cranking up AA and other gfx settings. you only got 1 gb (or 2gb if you bought the 2gb versions of 5770) for the cfx 5770s.
much improved gpu computing capability with 7970's gcn arch.
2x 5770 performs up to gtx 570-580 level heavily depending on games. the 7970 more or less outperforms the gtx 580.
now it depends on your pc's specs if it can support the 7970 and take full advantage of it (including your psu).

Not at higher eyefinity res where you need that 3GB vram.

Also, xfire 6870 does not beat 7970. 7970 is almost about 6990 or GTX 590. Thats dual 6970's or GTX 570s

And I know 6770 xfire is weaker than 6970 so 7970 will beat quadfire. And after 2 cards, the performance increase added per card drops. A third 6870 only adds 20% increase to performance.

hd 7970 will be the best choice because its of newer tech with good performance and some games doesnt support cf and sometime there will be issues with crossfire so it will be better to go with single high end card and even the hd 7970 performs better in higher resolution. 

benchmark:- http://www.tested.com/news/tested-amd-radeon-hd-7970-vi...

review:- http://www.legitreviews.com/article/1805/15/







agreed with everyone who said that it is an single high end gpu in the market. 

edit:- go with hd 7970 forget about crossfire hd 5700s. 

OMG YOURE SO LUCKY

keep the xfire 5770s and send me the 7970? ;P

Wow, I had no idea that not even two 570s can match one 7970.

Two GTX 570s can easily beat an HD7970. The discussion is about HD5770s.

I'll give you $300 for the 7970 even if you've put it in your system. MSG me. Oh, and I'll throw in another 5770 for you to add to your system. I in fact DO have eyfinity and need that 3GB VRAM.

Who in the world gave you that?

Yes im sure someone will just sell ya 7970 off an international forum. BUt hey ya never know.

It could happen... But it was mostly in jest. Chill Brah.