I posted this question on NVIDIA forums too but perhaps there's a chance someone else might have the same issue. I cannot tell if this a UEFI or driver problem?
I have a strange problem with Strix X299-E motherboard and SLI with the latest NVIDIA driver 384.76 (actually, with any driver but the X299 platform is brand new and hit retail around week ago so I guess this is the correct to use).
The thing is, SLI scaling is only around 45 % to 75 %, usually sits around 60 to 66 % per card only. The 1080TI cards and PSU have been working perfectly fine on old X99 before I swapped the motherboard and CPU. Everything else is the same. I have tried Windows 8.1 and Windows 10 to no avail, changed all UEFI settings, checked PCIe lane speeds, tried HB and single SLI bridges, disabled G-Sync, disabled V-sync, changed game settings, disabled antialiasing, updated UEFI, changed motherboard voltages and what else. Nothing else to try I guess.
Only some titles like Metro 2033 seem to work somewhat normal, the rest don't. Even Fire Strike 1.1 doesn't but then again Fire Strike Ultra does? In Fire Strike 1.1 combined test the scaling is around 35 % per card and the scores are way off.
😞Setup:
i9-7900X
Asus Strix X299-E motherboard
64 GB DDR4-3200 MHz (yeah, a single kit, CMD64GX4M8B3200C16)
Asus Strix 1080 TI OC SLI
Asus motherboard bundled HB bridge
Corsair AX1500i
Asus PG279Q G-Sync
Main: i9-10980XE - Rampage VI Extreme Encore - 64 GB G.Skill Trident Z Royal 3600 CL16 - Strix RTX 3090 - Phanteks Enthoo Primo - Corsair AX1500i - Samsung 960 PRO 1 TB + Intel 600P 1TB - Water cooling
HTPC: i7-6950X - X99-M WS - 32 GB G.Skill RipjawsV DDR4-2400 - GTX1050TI - Bitfenix Pandora - Corsair AX860 - Intel 750 400 GB + Samsung 1 TB 850 EVO
All around: i9-7980XE - Rampage VI Extreme - 64 GB G.Skill 4000 CL18-19-19-39 - Strix RTX3090 - Phanteks P500A - Samsung 960 EVO 512 GB - Water cooling
