Sign in with
Sign up | Sign in
Your question

Crossfire conundrum - what shall I do?

Tags:
  • Radeon
  • Graphics
Last response: in Graphics & Displays
Share
October 8, 2013 8:34:41 AM

Ok guys. So at the moment I've got:

Windows 8 pro
4770k CPU
16gb ram
some ssd's and a HD
xfx radeon 7970 ghz ghost cooler.
700w seasonic psu

Was thinking about adding another 7970ghz. Main reason is so I can run the 24x AA in all games. It looks awesome but does take the frame rate down and it's quite stuttery. CPU is not maxed at all (have looked in task manager)

The problem is - I have 3x PCIe ports on the mobo.

1x PCIe is 16x and this is what I have the radeon plugged into atm.
The next PCIe is 8x
And the other PCIe is 4x

So what I should do is plug the 2nd radeon into the 8x yes? BUT - the problem is - it would be SO close to the 1st radeon that it would block the two fans on the side. If I plugged it into the 4x slot there would be plenty of room between the cards but I am thinking - won't this slow the 2nd card down a lot? Cos it's only 4x PCIe instead of 8x.

Would anyone be able to tell me? Am I wasting my time doing this? I could squeeze it in the 8x slot but I would be worried it would over heat!!

Thanks :) 

More about : crossfire conundrum

October 8, 2013 9:12:04 AM

What motherboard do you have? You will definitely want to put the second card in the x8 slot. I have a Z77 extreme 4 and thought it would be really tight before I put my second card in, but once I did I see there is actually some space. All I did was create a custom fan profile to make the fans spin a little faster and now the cards rarely get over 65C.
m
0
l
October 8, 2013 9:13:07 AM

Also, what power supply are you running?
m
0
l
Related resources
October 8, 2013 9:15:56 AM

He listed the psu. It will be fine. Two cards with a max TDP of 250W totalling 500W and the rest of the system definitely won't use 200W.
m
0
l
October 8, 2013 9:27:56 AM

wanderer11 said:
He listed the psu. It will be fine. Two cards with a max TDP of 250W totalling 500W and the rest of the system definitely won't use 200W.


Didnt notice the PSU.

Also, on average the cards wouldnt pull that much power. They'd probably pull close to 400W, and maybe 500W on peak load. The TDP of the cards added does not add up to the power used.

Take a look at this cool chart:
http://forums.atomicmpc.com.au/index.php?showtopic=264
m
0
l
October 8, 2013 10:03:42 AM

Interesting article, but I see 520W peak for 7970 CF.
m
0
l
October 8, 2013 10:50:08 AM

wanderer11 said:
Interesting article, but I see 520W peak for 7970 CF.


This is true, but for other cards with a similar TDP and power requirements are not so. What I was mainly just saying is that the power needed is not the TDPx2. Its a good estimate, but not always an exact science.

Not trying to argue, just discussing :) 
m
0
l
October 8, 2013 10:54:53 AM

I understand. I liked the link. I thought 7870s drew more power than that. Looks like a 550W psu would easily power 7870 CF. Guess I didn't need a 750W after all.
m
0
l
!