Buying second card, 5870 or 6870?

[kiban]

So, I own a hd 5870, and when I bought it, I was planning on crossfiring it on a later date. But now I'm looking at the 6xxx series and I don't know what to think. The cheapest 5870 I found is at 300€(431$), and the cheapest 6870 at 145€(208$).
I looked up a few reviews, and I'm seeing that the 6870 performs like 4 fps less than the 5870. Is this true? to what extent if so?, cos if it is, I would be better off trying to sell my 5870 and buying 2x6870, right?

 

[Pyree]

Crossfire won't work on different generation. You need to get 5870.

http://sites.amd.com/PublishingImages/Public/Graphic_Illustrations/WebBannerJPEG/AMD_CrossfireX_Chart_1618W.jpg

I doubt you can sell a second hand 5870 for the price of a new a new 5870 to get yourself 2x new 6870. But I think it is better to get 6870 because it seems like you are having trouble finding new 5870 in your region and for over $400 for a 5870 is overpriced.

 

[treefrog07]

TH has a comparison that may help you here. Be aware that AMD changed its model numbering scheme with the 6XXX series and the HD6870 is not the same tier performance as your HD 5870 card.

 

[spentshells]

for the price of a second 5870 you can get two 6870's then sell the 5870 and called it a day
with tesselation ( I dont care) 6870 performs better,
http://www.anandtech.com/bench/Product/301?vs=300

6870s looks to be the better option (including cash from the Orig 5870

 

[kiban]

Thanks for the replies. I do have the cash to buy the new 5870, I didn't mean getting cash through selling my current one. Nevertheless, I decided to go for 6870crossfire, since it doesn't do too badly compared to 5870. New tech and less performance hit from anti aliasing looks appealing too (and 2 new cards instead of 1 old 1 new).