post #21 of 21
Quote:
Originally Posted by avirex81 View Post

I'm in the same predicament. Can an I5 2500k run 3 7970s? Its OC’d to 4.8 and pushes my 7990 to 99 and 96-99 on the other GPU. Should I upgrade my cpu to run a 7970 on top of my 7990 or is my I5 2500k be sufficient enough? The board that is supporting this is a EVGA Z68 sli series board. Would upgrading the board help at all? Any advice would help, thanks!

I'm going to run thru the basics to get to your answer. If your board supports pcie 3, but you're on an SB cpu, you are limited to pcie 2. At pcie 2 you only have x16 pcie 2, and that gets split between two cards. One card is dual gpu, so it's forced to run x4/x4 in essence while the single gpu card runs at x8. This is far from ideal and will definitely mean you are wasting a lot performance. It's like burning money up, Floyd Mayweather style. If the board supports Ivy and it's pcie 3, then that is the ideal route. With Ivy at x16 pcie 3, the split will feed your each core of your 7990 with x4 pcie3, which technically equals x8 pcie 2. This is a bit better but in tests by borandi of anandtech, runnning the MIVF which does not have a PLX which forces aud gpu to run at x4 pcie3, the results showed that there was enough loss that it affected scoring.

Bottom line staying on sb cpu with trifire and up is bad. It is better with Ivy, but still not great. This is why yall should just get a 290 or two and be done if you don't want to change platforms or cpus.
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