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Crossfire on 16x/4x

Tags:
  • Crossfire
  • Graphics
Last response: in Graphics & Displays
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October 13, 2014 4:36:48 AM

hey guys,

Now before you ask, yes I have read numerous posts about other people asking this same question already. But I still think my situation might differ from theirs.

So I have an r9 290x atm with a 1000watts cpu bronze certified and I was thinking of getting a second r9 290x. I only use 1monitor but the second gpu was meant to increase my fps so I can fully utilize the 144hz monitor I want to buy with it. The thing is my motherboard is an Z75 pro3 so it only has one 16x 3.0 pcie slot and one 4x 2.0 pcie slot. All the other posts I read about this particular situation said the 4x would bottleneck my graphics perfomance which sounds logical BUT, When I changed cards from 7970 to my current r9 290x I accidentally put the r9 in the 4x slot for like 2months before I realized it was in the wrong slot and guess what? no fps difference between the slots whatsoever! So now Im confused, will the 4x really bottleneck my second card? then why didnt I see different fps during the time my current r9 was in the 4x slot? will it only bottleneck when I CF?

thank you for your help.

More about : crossfire 16x

October 13, 2014 7:53:02 AM

Doing Crossfire on a high end card like the 290x with 16x/4x is alright, but you will get around 5-20 fps drop because of that. If you will get the 290x i'd also invest in a good crossfire capable motherboard with at least 8x/8x or 16x/16x if you have an i7. (8x/8x to 16x/16x isn't that much of a hit though).
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October 13, 2014 8:01:32 AM

hmm, but you have completely disregarded my point about me not noticing any fps drops during the time I slotted my current r9 in the 4x slot. I understand a new motherboard with 8x/8x or even 16x/16x will improve performance by a bit but as long as I get a fps increase of 70-90% with the 4x Im fine with it. but what you are saying confirms what I thought, the 4x will be fine disregarding the 5-20fps drop you mentioned(which is fine by me). right?
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October 14, 2014 5:21:16 AM

You did not notice a bottleneck because it is not visiable that way, and because you are only running one card. Do a benchmark using each of the slots and you will see. x4 slot may seem fine to you, but it is a bottleneck and your performance will take a hit because of it. I did more digging, and the hit on your performance maybe even more. In some cases on x16 can perform better than two on x16/x4. You can go ahed and get the another gpu and it will work. But the performance will be dissapointing, and the bottleneck would be unfair for the second card. I highly recommend you get a better board ..
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