blah!
I just bought another 390x. Tested and it works alone.
I have 2x MSI R9 390X OC, same BIOS version.
I can't for the life of me to get crossfire to run. I'm running 18.9.3 and I have crossfire enabled in Radeon Global Settings. It sees both cards.
MSI Afterburner doesn't show any usage, fan, and holds a constant 35C temp for the second card...shows activity for the original card. Tested with Rise of the Tomb Raider and nothing, I've tried something like 3DMark and no usage. Windows Task Manager doesn't see any usage but shows it there. It shows up in Device Manager as okay.
I have a Gigabyte Z97X-Gaming 3 motherboard with F6 BIOS. Windows 10, up to date.
I found something on another site to check on "Disable ULPS" within MSI Afterburner and reboot...same results (still checked on).
Setting a specific profile within the Radeon Settings for say, Rise of the Tomb Raider (AMD profile) does nothing. I don't know what I'm missing and it's annoying...lol
Please list which OS and power supply you are using. The 390X uses a considerable amount of power, even more so if overclocked and in CF, so if you've got a power supply with a split +12v rail you might not be getting enough power to the GPUs
Seasonic M12II-750 EVO Hopefully I didn't overlook the requirements a few years go when I bought this *facepalm*
Windows 10, fully updated.
I think the r9 390X calls for a PSU of 600w, so for crossfire that could easily run up to 800w+ depending on what your other hardware is using.
This article tests a pair of OC'd 390X's and calls for a minimum of 800w, so you might need to grab something that can feed a bit more peak power to them.
Ha, I was just looking at that same article and banging my head off the desk. Found the EVGA Supernova 1000 G3 or 1000 GQ...probably pick up one of these....man I'm a noob.
Thanks dstmnd89x