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Crossfire config, mobo, powersupply

Tags:
  • Configuration
  • Crossfire
  • Systems
  • Powersupply
Last response: in Systems
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September 4, 2014 5:14:09 PM

Hey all, Thanks for taking the time to look at this post. I have just a few questions for you all... Right now i own two 7870 GHZ OC edition. Both are great cards and work perfectly by themselves.. but when ever i try and crossfire them i get worse performance in every game...
i've done it all.. uninstalling old drivers for each card.. reinstalling them fresh for both.. inserting one and checking and then inserting the other ( different times of course) nothing gives me the boost i want..(also tried different crossfire bridges..)
i have a
:600w thermaltake tr2
:m5a97 le r2.0
I also dont think its a CPU bottleneck i have a FX 6300 OC to 4.5ghz and it never reaches more than 70% in ANY game i play..
Also because the powersupply doesnt have 4 6pin connectors i had to use molex to 6pin could that be the issue and i just need to upgrade my powersupply? i know the mobo is a 4x4 when crossfiring but that shouldn't decrease my performance right? would it be a safe bet just to upgrade both(mobo and powersupply) ? Thanks a lot guys hopefully you can help me figure this out without me buying new equipment!

More about : crossfire config mobo powersupply

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September 4, 2014 6:47:47 PM

You are on the right track. Your MB's PCI e X16 slots are X16, x4 lanes. That is a performance killer. I have had personal experience with that lane configuration years ago with 2 x HD 6850 cards. Same issue. No increase in performance, and some games actually were hurt by the 2nd card. The slow slot causes the faster card to wait for the 2nd card to catch up and kills performance.

Like you, I also had 2 x HD 7870 Gigahertz cards in CF on an X8, X8 board and there was excellent performance. Later I moved them to a board with X16, x16 lanes and performance again improved, but only slightly.
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September 4, 2014 7:46:41 PM

So you think the powersupply is fine and its just the mobo? Thanks for your response.
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September 4, 2014 7:51:49 PM

While that is one of the worse PSUs you could have (5th tier: not recommended https://community.newegg.com/eggxpert/computer_hardware...)
... I'm sure the performance issue is MB related. Low end cards will do fine at x16, x4. But higher performance ones that need all the bandwidth they can get, will be bottlenecked by the lack of PCIe lanes.
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September 4, 2014 8:18:09 PM

I may just Replace the Mobo, and power supply to be safe.. what do you think the performance gain will be running them in Crossfire? besides a single what im using right now.
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September 5, 2014 12:53:55 PM

kowashie said:
I may just Replace the Mobo, and power supply to be safe.. what do you think the performance gain will be running them in Crossfire? besides a single what im using right now.


My 2 x HD 7870 OC cards pretty well got me the 80% improvement that is generally expected over a single card in most games.
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September 5, 2014 4:03:19 PM

alright thank you!
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