Radeon HD 4890s in Crossfire vs Radeon HD 6850?

[justinxtreme]

I currently have two Radeon HD 4890s in my system, and was wondering if it would be worth upgrading to a single Radoen HD 6850?

Both models are 1GBs and I'm getting the 6850 used, through a trade for one of my 4890s and a 9600GSO (for PhysX)

It's a good deal I know, but is it worth it? Losing Crossfire?

Specs
Intel Core 2 Duo E8400 @ 4.0GHz (1.27v) (Artic Cooler Freezer 7 Pro)
8GB DDR2-1066 Dual Channel (1:1 CPU/RAM ratio)
Asus P5Q Pro Turbo Crossfire Motherboard
800W PSU

The computer's power consumption isn't high at all and my computer is super silent under load, it doesn't even sound like there's two graphics cards in there, so I'm not looking to upgrade for a quieter system or lower power consumption. I read a couple forums saying how the Radeon HD 5870 is two times as powerful as the 4890 so I'm hoping upgrading to a single 6850 will produce similar results, plus DirectX 11 support.

 

[dgbkiller]

The Radeon hd 5870 is faster than the radeon hd 6850 and both have DX11.

5870 > 6850 in single card mode
2x5870 ~ 2x6850 CROSSFIRE

The 5870 is a decent amount better than 6850. AMD changed the number scheme for the cards on this round. So a 6850 is not an upgrade from a 5850 like you might think. It's closer to say 5850 - 6950 is the real upgrade path.

So if those cards are almost the same price, and they are close, you'll get more performance out of a 5870 for sure.
5870 is the faster card... The 6870 slightly edges it. If you want the next step up from a 5870 you would want to go 6950 or 6970.

 

[justinxtreme]

So the Radeon HD 5870 is faster than the 6850 and the 6850 is still two times faster than a single Radeon HD 4890?

 

[wolfram23]

Ummm a 5870 is between 6870 and 6950 performance.

4890CF should be a fair bit faster than a single 6850.

At best it would be a side-grade, not an upgrade. You do gain DX11, but honestly, you wouldn't have the power to use most of the features like DoF and Tesselation anyway. Although, there's only a few games that even use those to any decent effect, DX9 and DX10 are still widely used and usually look really good.