Hi everyone. I'm having trouble getting this CPU stable. At first I thought it was an overclocking issue, because when I overclocked to 5.0Ghz, the system locked up shortly afterwards, and I wasn't able to boot into Windows again without getting a frozen screen immediately upon logging in. I was able to revert the clock back to 4.7Ghz in safe mode, but was still having the frozen screen problem outside of safe mode. Since then I have been tinkering with different things in BIOS to try to get this system stable. My current setup is this:
CPU Frequency Multiplier: x22.0 4400Mhz
CPU Voltage: 1.4375V
NB Frequency Multiplier: x11.0 2200Mhz
CPU NB Voltage: 1.1375V
HT Bus Speed: 2600Hmz

With my setup like this, I am stable at idle, and with basic web-browsing, checking e-mail, etc. Trying to do anything more complex like installing a program, or stress-testing with OCCT results in a lockup 5-20 seconds after starting the process.

System specs:
ASROCK Fatal1ty 990FX Professional, 2.0 BIOS
FX-9590 processor underclocked to 4.4Ghz
Corsair H80 liquid cooling, 44C at idle, typing up this post it has gone up to 52C max
16GB ram
Corsair AX1200 power supply

Thank you for your help.