Figured I'd throw this out here in this thread instead of opening a new one. You can see my rig below, the 5960x on an ASRock X99 OC Formula. My problem is both of my 780 Ti's are running in x8 mode of PCIe 3.0. A while back the MSI one that is in the first PCIe slot was running 16x and the Asus one in the 3rd slot was running at 8x. It didn't really bother me because there is little to no loss of performance in 2 way sli 16x to 8x on PCIe 3.0 so I let it slide and blamed my M.2 Nvme SSD that takes 4x PCIe lanes up but now they are both running at 8x which is really puzzling. For one, even with the NVMe drive I should have plenty of lanes left over for both cards to run at 16x. According to the manual the NVMe M.2 Ultra slot turns off the 3rd PCIe slot and uses 4 lanes. I have my cards in PCIe slots 1 and 4 which should both be 16x according to the ASRock stats page for my board that I will paste here below:
Expansion / Connectivity
Slots - 5 x PCI Express 3.0 x16 Slots (PCIE1/PCIE2/PCIE3/PCIE4/PCIE5: single at x16 (PCIE1); dual at x16 (PCIE1) / x16 (PCIE4); triple at x8 (PCIE1) / x8 (PCIE2) / x16 (PCIE4); quad at x8 (PCIE1) / x8 (PCIE2) / x8 (PCIE4) / x8 (PCIE5))*
- 1 x Half Mini-PCI Express Slot
- Supports AMD Quad CrossFireX™, 4-Way CrossFireX™, 3-Way CrossFireX™ and CrossFireX™***
- Supports NVIDIA® Quad SLI™, 4-Way SLI™, 3-Way SLI™ and SLI™***
*If you install CPU with 28 lanes, PCIE1/PCIE2/PCIE3/PCIE4/PCIE5 will run at x16/x0/x4/x8/x0 or x8/x8/x4/x8/x0, and PCIE5 will be disabled.
**If Ultra M.2 PCI Express module is installed, PCIE3 slot will be disabled.
I've read up and can't find any reason for the second one running at 8x much less both now running at 8x. I have no other peripherals that take up andy PCIe lanes so with a 5960x I should have more than enough to run 2 cards in slot 1 and 4 at 16x and 1 NVMe M.2 Ultra drive at 4x with the 3rd PCIe slot disabled. The only thing that has changed since both going to 8x instead of just one is video drivers and Windows versions. I'm running the fast ring insider preview of Windows 10 so I'm constantly upgrading Windows but I periodically do a full format and fresh install to remove any lingering bugs from older versions. I really don't think the OS has much to do with it, just giving all the information I can. I do have both of the cards flashed with skyn3t's custom BIOS for 780 Ti's but I don't think that would affect them, it never did on a single card and have all my PCIe slots put on Gen 3 in the UEFI. I've tried disabling the 4th PCIe slot with the little switch on the board and running just the single MSI card in slot 1 and it still will only run at 8x. I'm at a loss as to why either is doing it. I was confused but not concerned when I first bought my 2nd card and it would only run at 8x and the 1st card would still run at 16x but now with them both running at only 8x I'm really lost. I've thought about taking out the NVMe drive and using a thumb drive windows install to see if they will both go to 16x or stay a 8x to rule it out as the problem but if anyone else has any other ideas or knows something I'm completely missing, please assist me. I'd greatly appreciate it.
Edit: Something just came to mind to try. Disable all other PCIe slots not in use in the UEFI and/or the dip switches just in case they are pulling some lanes away for some odd reason. BTW, I have updated to the newest BIOS/UEFI and reset it to factory defaults more times than I can remember so that will not help. I'll reply back after work tonight after I try forcing all empty unoccupied PCIe slots off in the BIOS and with the dip switches.Edited by Strat79 - 8/11/16 at 6:26pm