Just decided to try adding a second GPU to my system. My new card is an RX 580 while the old one is an RX 480. The RX 580 is in the primary slot. Everything runs fine in single GPU mode but if I boot up a game like Overwatch while crossfire is enabled in the global settings, the system hard freezes (no BSOD) as soon as the main menu loads (where there are 3D graphics being rendered). Is this a power supply issue? I tried making sure both cards are seated properly and the power connections are solid. It's 850 Thermaltake PSU. Any suggestions?