5850 or second 4870, what say ?

PC Hardware & Gaming Graphics Cards & GPUs
4

@OP:

It depends how the ratios work out.

  1. You sell the 4870 and add money and get the 5850

  2. You buy another 4870.

Now which ever is cheaper I would suggest go for that. 2x4870 scales pretty well. Specially on 1920 x 1080 (which you plan). I get a performance jump of approximate 20FPS on Warhead. Need I say more. 4870 Crossfire will rip.