Crossfire Questions

[cwgk91]

Hey all, fresh back to PCs (been an apple user for quite some time, BF4 tempted me back though!) and have a few questions about crossfire and how it works. Had a quick search but haven't found all the answers I've been looking for.

Ive currently got a HIS IceQ 7970 Ghz edition which I'm very happy with, been managing to play BF4 on ultra at 1080p with no problems at all at around 60fps (though a little drop in frame rate when looking through some sights - I assume that this is a software problem).

With christmas coming up and sales thereafter, I was wondering about acquiring a second 7970 to crossfire with my current setup but I first have a few questions:

1. With my second graphics card, does crossfire work so that it effectively doubles up all my current VRAM etc to make one graphics card with 6Gb of memory or does it run them in parallel to give faster frame rates?

2. I only have a 4670k running at 4.2Ghz, will this cause bottlenecking? And if so with mantle coming out, will this remove the bottleneck?

3. Ive been looking at the new 280x which for all intents and purposes is a rebadged 7970, is there any downside from buying one of these to Xfire with my current setup compared to another 7970 Ghz considering the 'newer' card is £50 cheaper?

4. Could I Xfire with a 7990 to get an effective Tri-fire?

Thanks all!

Charlie

 

[teppic]

1. No, the RAM remains the same as with one card (though this may be different with Mantle).

2. To some degree, yes. Mantle may remove it, we'll have to see.

3. No.

4. Yes.

 

[Fulax]

1. You still only have 3GB usable VRAM. You will get higher FPS, though.

2. Wouldn't have thought so. Not much.

3. 280X and 7970 works. Just go for the cheaper option.

4. You could.

 

[rolypolyman]

7990\7970 tri-fire, you know you want to, that Ghz 7970 would match very well with the 7990 being its 2X7970Ghz. You'd need a beefy psu though, I'd like at least 850W quality build like, seasonic, antec, Xfx, Bequiet, Corsair etc....

 

[RanxZy]

You could Tr-fire with a 7990 but 7970 + 7970 is really the sweet spot for scaling in games. You can pay less for another 280X than getting a 7990 and you may run into less problems with two GPU's rather than 3 in a lot of games that won't really take much advantage of the third GPU.

 

[cwgk91]

@rolypolyman: Ive got an 850W Gold NZXT PSU so that should (hopefully) be able to handle a 7990, though I have heard problems with games not working well with tri-fire. Also, will my 4670k run into problems bottlenecking?

@RanxZy: so you would recommend a second 7970 then? Or would a 280x work as well?

PS thanks for the fast replies!

 

[Ragnahex]

7970 and 280x are the same card just rebranded

 

[RanxZy]

Yes I a good 7970 Ghz edition or 280X will do the job fine. You should see a big performance increase in BF4 with crossfire.