ASUS Hero VIII - SLI problem

[KIS]

After replacing Gigabyte Z170X Gaming 7 with Asus Maximus Hero VIII on Windows 10 64bit running two 980ti's my SLI performance has significantly dropped. In games where I had 90 FPS in SLI as opposed to 55 FPS in a single card setup (at 1440p) my current SLI performance is on par with a single card (zero to 10% boost in FPS) but with visible stutter that I haven't encountered before (it's not micro-stutter but like when the whole picture jerks forward every 2 seconds or so). I've tried reinstalling the NVIDIA driver, rolling it back, changing the PCI configuration in BIOS to gen 3 for both GPUs, repositioning the SLI bridge on alternative spots on the GPUs, downgrading BIOS. Nothing seems to work.

Then I noticed that my second PCIe slot on the MB (x8) is actually running at x4 while the first slot (with the master GPU) is running at x8 (which is normal in SLI). I understand the second PCIe lane (with the salve GPU) should also be running at x8. I guess this must be the issue but I have no idea why since these PCIe slots are not shared with other slots/peripherals. Is it a faulty MB?

[Mick Naughty]

Well if the correct slot is used, and the cpu has enough lanes it would work. Assuming you don't have anything else on the board taking away lanes like an m.2. Bios update perhaps.

[reptileexperts]

Sounds like you may have consumed some of your PCI-e lanes ether with too many sata connections or as referenced above an m.2 addition. Update bios and check again. After that, consult your mobo manual and see what effects your PCI-e lanes (i.e. certain sata ports, m.2 slots)

[KIS]

7 hours ago, reptileexperts said:

Sounds like you may have consumed some of your PCI-e lanes ether with too many sata connections or as referenced above an m.2 addition. Update bios and check again. After that, consult your mobo manual and see what effects your PCI-e lanes (i.e. certain sata ports, m.2 slots)

Nope, the first two PCIe slots on this MB only share bandwidth and lanes between themselves (as on all others I presume). M.2 cards, etc. may, as I understand, share bandwidth with the third PCIe slot (which runs at x4). I tried everything: reinstalling Windows, flashing BIOS back, reassembling the CPU and GPUs.

 

Today I went to the retailer and they said their Windows shows both cards working at correct x8 and BIOS apparently simply reporting wrong speeds or that they would increase to x8 under load. I thought that was b*llsh*t as I had used the same software and it showed one card running at x4 (as did BIOS) which I think was the issue with the SLI . ASUS told me to go to the retailer (that's their policy in my country) and the retailer told me the card is fine (and who cares about x4/8/16, there is no difference anyway right) and that I can go to...ASUS. I bought another Gigabyte Z170X Gaming 7 which works just fine, no issues in SLI, both cards working at x8. I only regret purchasing an ASUS card after my first Gigabyte had an accident with a LAN port.

[Mick Naughty]

Sounds like a cpu seating issue. 

[KIS]

34 minutes ago, Mick Naughty said:

Sounds like a cpu seating issue. 

Well I reinstalled the CPU twice with that MB, cleaned all, etc. With the Gigabyte MB I never had such issues. It is the same socket, same CPU. With the first and the second Gigabyte boards I only had to assemble the PC once and all was working fine. So to me sounds like a defective product issue...whether the PCIe lanes or the CPU socket, doesn't really matter.

[Lathlaer]

3 hours ago, KIS said:

or that they would increase to x8 under load.

Gotta be honest here, this is the first time I'm hearing about GPU changing PCIE lane utilization depending on the load.

[Mick Naughty]

4 minutes ago, Lathlaer said:

Gotta be honest here, this is the first time I'm hearing about GPU changing PCIE lane utilization depending on the load.

Depends on what you watch it through. Not new.