How will adding a second 4870 graphics card help my gamming

[GameNut56]

Hello,I have an asus P5B Deluxe MB,Core 2 Extreme CPU,4gigs ram,1000 watt PSU,4870 video card. I'd like to know what performance benefits I would get running two 4870's in"crossfire"configuration!

 

[4745454b]

The P5B is a 965 chipset board. While it has two PCIe slots, they run at 1.0 PCIe speeds. Not only that but it's setup for 16x/4x. This means those two cards will be running at 4x/4x speeds, and nearly all of the time will run slower then a single card at 16x. I wouldn't get a second card and run it on that card.

Edit: Wouldn't run it on that board I mean of course...

 

[GameNut56]

The P5B Deluxe has 2 x PCI- E x 16 (blue @ x16 mode,black @ x2 or x4 mode)

1 x PEI-E x 1 ( x1 or disabled mode)

3 x PCI 2.2

So if I use the (blue PCI-E slots,won't the run at 16x/16x

 

[GameNut56]

sorry,there is only one blue and one black slot on the P5B Deluxe.What would be a good asus motherboard to run 4870's in crossfire with my cpu.

 

[4745454b]

The blue one will always run at 16x mode. The problem is once you add a card in that second slot, it will only run at 4x mode. It doesn't matter now that you've linked them if the blue slot runs at 16x or 1,000x. Because it's linked to a 4x slot they must work together at 4x speeds. 4x/4x PCIe 1.0 is slower then 16x PCIe 1.0. As such I wouldn't buy another 4870 to run CF.

If you want more speed look at buying a 5850 or 6870, etc. These cards are faster then your 4870.

Edit: I wouldn't bother with CFing your 4870. Older slower tech now, not worth the time.

 

[GameNut56]

Thank you for the info.I'm learning slowly.

 

[Overclocked Toaster]

yeah dont bother with crossfiring, you will be missing out on dx11 as well

 

[GameNut56]

Best answer selected by GameNut56.