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GTX780 ACX SC unstable performance on MVIE Slot 3(B2)

Level 7
I have experienced some issue with this motherboard. The third PICE slot from the top, aka PCIe 3.0/20_x8_B2, is causing any graphic card that sit on it performing poorly. I noticed this issue when my two GTX780s in SLI configuration, installed on slot 1 and slot 3 as Asus suggested, gave me poor performance in a random pattern. 2 out of 10 system restarts its benchmark results would go very low than it should, meanwhile the CPU would also be busy occupied by system interrupts, making browsing the internet painfully slow. To narrow down the cause of this issue, I reconfigured the SLI to slot 1 and slot 4(at a disadvantage of not using the native PICe lanes of the chipset) and restarted and tested the system for 10 times. Everything turned out to be fine which eliminates the possibility of bad graphic card/driver. Then I put a single graphic card on slot 1 and tested 10 times, no problem. However, when I put the same card on slot 3 and tested it for 10 times, the poor performance issue appeared again in the same pattern as it was in SLI slot1 and slot3 configuration.

Does anybody here have this kind of issue also? Or should I contact the seller for a replacement?

BTW:My power source is AX1200i, and I'm testing it using dual EVGA ACX 780SC with the case open to keep them under 75 celsius degree.
422 REPLIES 422

Level 15
Agree with Pennyboy. Both bios versions he mentions seem to work fine here, 1203 and 1302. Tested in Valley bench and works well.
MZ790AE, GSkill F5-8400J4052G24GX2-TZ5RK, 14900KS, EKWB D5 TBE 300, Seasonic Prime TX-1600 ATX 3.0, Asus Strix 4090 w/ HK block, Phanteks Enthoo Elite, Asus Claymore 2, Asus Gladius 3, Asus XG349C, Crucial T705, Windows 11 Pro

Decided to try this out again, and moved my second card to the B2 slot.
Tried both 1203 and 1302 BIOS. Have been using the 1102 BIOS since before.

Much has been improved, but it is still not solved in my case.

About 5-10 minutes benching/gaming, stutter & fps drops start to appear.
Sometimes it gives me a "nvlddmkm.sys" error in my eventlog.

Heaven Bench, AC4: black flag, Borderlands 2, Metro:Last Light, behaves the same way.
Valley bench is the only one that seems stable so far.(?)

At least it doesn't crash/freeze my system or games/bench, as it did before.
And it doesn't give any weird sound crackling as it did before with the 1102 BIOS

Any one with some BIOS tweak, or any tip? , who wouldn't mind to share? 🙂

Level 7
So its been 8 months since i have had an issue with my system.... Now the pci-e slot B2 is acting up again.. Running through the PLX now :(.. I dont understand. I did not do anything but took out my vid cards to clean them and now the issue is back.