Crossfiring Radeon 6870 with a Corsair TX650 psu

[Cirque]

Hi guys

So I got my hubby a new mobo and we were thinking of crossfiring his now somewhat ancient Radeon card. I made sure the mobo supports that.

However, the PSU he has (Corsair TX650) only has 2 PCI-E connectors.

I have googled but to be honest I'm still not sure if it is possible with this PSU. his current gpu uses both PCI-E connectors. I've read somewhere he's out of luck, and yet somewhere else it is still possible, but HOW do you achieve that?

Thanks for any replies. We've never xfired anything before so we're unsure.

[Deleted]

It is possible and should be fine, I crossfired 2 x 6870 on a 600W crappy OCZ ModXstream. You can just go to your local computer store and get some molex (4 pin) to PCI-E connectors.

[vesseblah]

Unless you can get the 6870 for free or almost free I wouldn't bother. You can get so much more raw power in single card now that CF isn't really worth all the trouble.

[Cirque]

Unless you can get the 6870 for free or almost free I wouldn't bother. You can get so much more raw power in single card now that CF isn't really worth all the trouble.

Well it would be almost free, that's why we bother.

Kegan, thanks for the info. Could you translate that to more noobfriendly terms though? (My English is gonna be fail from now on, not really familiar with English technical terms) Do you get a convertor-like thing that you plug onto already existing plugs of your PSU so you can have the 4 required pci-e connectors, or do you split the existing ones with a splitter?

[n0cturnal]

http://www.newegg.com/Product/Produc...82E16812887001

Something like this, you plug in 1 or 2 Molex connectors and on the other end you get a 6 or 8pin PCI-E connector.

[vesseblah]

Well it would be almost free, that's why we bother.

For WoW it won't be worth it, and in some cases the game will run slower with two AMD cards than one.

If you're interested in some new first player shooters then CF might be good idea if you can get the second card dirt-cheap.

Kegan, thanks for the info. Could you translate that to more noobfriendly terms though? (My English is gonna be fail from now on, not really familiar with English technical terms) Do you get a convertor-like thing that you plug onto already existing plugs of your PSU so you can have the 4 required pci-e connectors, or do you split the existing ones with a splitter?

TX650 is a single rail PSU so you can use simple splitters or adapters for it.

These things come in the box with some graphics cards:


Or alternatively you could buy something like this:

[Cirque]

Thanks for the explanations!

Does WOW still have difficulties with crossfire? :/ Will it really lower performance?

Well he doesn't only play WoW, if it would diminish his WoW performance, it is possible to disable the crossfire function right?

[Nellah]

What other games does he play? Depending on the games (and the specs of the rest of the computer) it may be worth Crossfiring or it may cause you more trouble than anything.

[vesseblah]

Does WOW still have difficulties with crossfire? :/ Will it really lower performance?

In new cards (7k) it's no longer FPS loss and it's almost always a small gain, but no clue what's the status of old (6k) cards. Last year one driver might give 5fps more and the one before and after it 20fps less and so on.

Well he doesn't only play WoW, if it would diminish his WoW performance, it is possible to disable the crossfire function right?

Yes, it can be turned off for single games. But the card will still be on making noise and heat, just not as much as playing with two.


If the wanted end result your friend is looking for is getting higher framerates in WoW raids, crossfire of two 6870's will do big fat nothing for a single 1920x1080 or smaller screen gameplay.

[Cirque]

What other games does he play? Depending on the games (and the specs of the rest of the computer) it may be worth Crossfiring or it may cause you more trouble than anything.

It's stuff like heavily modded Civ, but he plays a wide variety of games (a big fan of Steam, so he's always playing something, GTA, Witcher, etc). He has a i7 3.5GhZ cpu, 12 GB RAM, and around 2 TB of Harddisk on Windows 8. His motherboard is brand new too, to support the new cpu - a gigabyte with (and i forgot the number, I mean, I can't even remember my own age...) the Z chipset.

It sounds like it's not worth the trouble at all though, which is a shame really. Guess we should save up for a new card then?

[Deleted]

When I still crossfired 2 x 6870 I had nice gains in games like Civ 5 and racing games like F1 2011 and Shift 2. In WoW however, it gave me a gain in fps but it made it all look very choppy and stuttering, whatever profile I tried.
I also tried playing FarCry 3 with it, it gave me some slight microstuttering, alltho it could handle it good on pretty much the highest settings. When there where big open fields the game started dropping in FPS tho, but this you can blame on the limited amount of video memory, 1GB is just to low in these times.

I returned both cards, since I work in the store I bought them, it was not an issue, and got a 7950 instead, which gave me better results in all games and the price was about the same as 2 of those cards.