Graphics Cards

[amerikuyu]

I installed an AMD Radeon RX 590 today and while I believe I did everything correctly, I'm unable to use both of my monitors. My first step was to connect the GPU to the PC via a Riser Cable, then I connected the power (14 pins 8+6). Installed the drivers, updated the drivers. Seems simple enough. But whenever I try to boot up with my second monitor, it works for about 3 minutes, then the monitors go black with "no signal" and then sound stops and the computer is completely non-responsive. This typically happens when the fans start turning. The computer remains on and the fans (both for the GPU and the CPU) start going faster and faster. It should be noted that with only one monitor, there are no problems whatsoever, even running a fairly demanding game (Overwatch) at 120 FPS. I've looked into re-installing the drivers, removing my Nvidia ones (my last GPU was a 1050 TI), and I looked into my power supply. I'm supplying 750W while my rig (including the new GPU) isn't even using 500. I'm at a loss and any help would be appreciated.

[elstaci]

You need to give more information on your computer hardware and software including Windows version, AMD Driver version, MAKE & Model of motherboard, CPU, GPU, & PSU.

At 750 watt PSU should be plenty of power unless it is defective in its outputs.

Also what do you mean that you have the RX590 connected via a RISER Cable?  Something similar to this:

How are the monitiors connected? Via HDMI, DP, DVI, etc?  Any adapters installed connected to the monitors?

Can you connect the GPU card directly on the motherboard's PCIex16 lane and see if both monitors works correctly? Could be the Riser may not be compatible with the RX590.