R9 290 Crossfire on Z97 PC Mate not working - GPU or motherboard issue?

[tokyorock]

I recently purchased a second R9 290 to run in crossfire, but I haven't been able to get them working together.

Each card works fine on its own (able to overclock each to 1050/1300 at stock power limits), but when I put them both in, Windows disables one of the cards (Code 43) and AMD drivers never display the option to enable Crossfire. Both GPUs are running identical VBIOS versions (if that matters), and my motherboard is running the latest BIOS version.

With both cards plugged in, it's always the second GPU that is disabled (whichever one is in the second PCIe slot). Here is GPU1 and GPU2 in GPUz.

When I try to run a single GPU in the second PCIe slot (first slot empty), it works fine. Also, I tried booting without my PCIe WiFi card plugged in (in case it was eating up PCIe bandwidth), but it didn't seem to affect anything.

Am I missing something? In BIOS, there is only an option to force PCIe mode on the first slot, but I can't find any settings concerning the second slot.

Here's my build:

CPU: Intel - Core i5-4690K 3.5 GHz Quad-Core Processor
CPU Cooler: Cooler Master - Seidon 240M 86.15 CFM Liquid CPU Cooler
Motherboard: MSI - Z97 PC MATE ATX LGA1150 Motherboard
Memory: PNY - 16 GB (2 x 8 GB) DDR3-1866 Memory
Storage: Plextor - M5S Series 128 GB 2.5" Solid State Drive
Storage: Hitachi - Deskstar 7K2000 2 TB 3.5" 7200RPM Internal Hard Drive
Video Card: XFX - Radeon R9 290 4 GB Double Dissipation Video Card (2-Way CrossFire)
Video Card: XFX - Radeon R9 290 4 GB Double Dissipation Video Card (2-Way CrossFire)
Case: Corsair - 270R ATX Mid Tower Case
Power Supply: EVGA - 850 W 80+ Gold Certified Semi-Modular ATX Power Supply
Operating System: Microsoft - Windows 10 Pro OEM 64-bit
Wireless Network Adapter: TP-Link - TL-WDN4800 PCI-Express x1 802.11a/b/g/n Wi-Fi Adapter
Case Fan: Cooler Master - R4-S2S-124K-GP 44.73 CFM 120mm Fans
Monitor: Acer - XF240H 24.0" 1920x1080 144 Hz Monitor

 

[tokyorock]

After trying everything under the sun to get my computer working, I finally found a solution. I rolled back my drivers to 16.1.1 (released in 2016!), and now crossfire is working.

I'll try contacting AMD support next. At least I've ruled out a hardware issue...

 

[Zaoped]

Any updates on this? I just experienced this exact same problem running 2 XFX R9 290 GPUs on a MSI Z97 Gaming 9 AC motherboard and rolling back to 16.1.1 does appear to have fixed the problem, but if there is a newer driver package that works it would nice to be able to update. Thanks for posting your initial results, I had tried everything and was losing hope!