I´m thinking of upgrading my gtx260 to SLI with an extra one or alternatively exchanging the gtx with a 5870 and upgrade to crossfire from there.
Now here´s my dilemma:
My motherboard GA-P55m-UD2 has 1 PCIe 16x and 1 PCIe x4 port. Now it´s says CrossfireX ready on the box but nothing about SLI. Is it possible to upgrade this way and get my moneys worth or do I have to get a new motherboard?
Another question: Why is this card crossfire ready and not SLI ready?
No, I wouldn't do it if I was you. Your board will not work for SLI because Nvidia makes motherboard manufacturers pay money to enable SLI on their boards so the lower price boards usually don't support SLI. As far as Crossfire goes, you will be severely bottlenecked by that x4 slot. You have a few options.
1. The 5870 is faster than 2 gtx 260s in SLI and you can keep your motherboard. You could sell your 260 or keep it and put it in the x4 slot for Physx and CUDA operations. x4 is plenty for that.
2. Buy a GTX 470, it is around the same speed as the 5870.
3. If you really want blazing fast graphics you could sell your 260 and put the money towards a 5970 (2 5870s on one card), or a GTX 480.
I wouldn't recommend buying a new board to SLI the 260s, they are old tech and you will be kicking yourself in a year. Check out some reviews online and see how the games you play run on the different cards.
It's a bad motherboard to crossfire on. The second PCI-E slot is 1.0, meaning that it will indeed bottleneck any high-level graphics card you put in there. If I were you, I'd save some money and grab a high-end HD5870, a GTX480, or, preferably, an HD5970. The 5970 will give you the most performance, because it would be a bad idea to add a high-end GPU on a low-end PCI-E slot.
Thanks for the advice - thought that might be the answer though. Pretty pissed at the company I bought the PC from - they say on their website that they´re always open and honest about any bottleneck in thier machines - BULL!
I should probably complain. Selling me a nvidia card with the PC without any chance for an SLI upgrade or, even with an ATI card, only a shitty setup for crossfire upgrade.