Question Bad PSU likely fried my computer - where do I go from here?

Mar 29, 2020
Background: This is a family pc that was built 9yrs ago and has been recently upgraded to improve performance and make it viable for gaming. I replaced the original ram ( 3 sticks of 2GB G Skill ddr3 1600) with 3 sticks of Patriot 4GB ddr3 1600 modules over a year ago to improve stability. I believed at the time that is was the cause of system freezes, but looking back it could have been a symptom of a failing psu (some intensive programs caused the computer to lock up completely - needed to be manually powered off). I recently cloned the original HDD to a sata ssd to improve boot times and overall responsiveness of the system (boot times down from about 4 minutes to 30 seconds). Afterwards, the dated GTX 460SE (1 GB of vram) was replaced with a Sapphire Radeon RX 580 (8gb) and the old monitor (Hanns G hw191a - absolutely abysmal) was replaced with the ASUS VP249QGR (1080p 144hz) monitor.

CPU: Intel I7 990x (stock clocks)
GPU: Sapphire Radeon RX 580 8GB (stock clocks)
Motherboard: ASUS P6X58D-E
Ram: Patriot 3x4GB 1600mhz PC3-12800 (stock clocks)
PSU: Corsair TX650 - 80Plus Certified (has gold stickers not the bronze certified model) - attached to surge protector
Monitor: ASUS VP249QGR 1080p 144hz
Case: Antec 900 (good ventilation for all components)
CPU Cooler: Hyper 212 Plus (one fan attached to cooler)
SSD (Current Boot Drive): Western Digital Blue 3D Nano 500GB SATA III
HDDs: [Two] Western Digital Cavier Black 500GB (One is used as a general backup for media file and the other is the original boot drive that was clone; this drive has been luckily kept disconnected from the motherboard and PSU in case of the ssd not booting or catastrophic hardware failure)

Problem Timeline:
-Over a year ago: System freezes that I can not entirely explain when using Affinity Photo (photo editing program similar to Photoshop); somewhat mitigated by ram replacement.
- Unknown: One instance that I remember in which system did not boot; probably just a fluke.
-Yesterday and throught last week: random computer shutdowns during gaming (Planet Zoo and one instance of Minecraft); one day it happened 3 times in sequence while other days this phenomenon was not observed at all. I will note that these instances followed the GPU replacement by about a week.
-Yesterday - the computer's last shutdown: In an attempt to understand the problem I recreated the common scenario that caused it to shutdown; after 30 min of messing around in Planet Zoo the system turned off. When I tried to power it on the pc turned itself on and off repeatedly (the inteval between about 2 seconds) and the case lights flickered rapidly and behaved like the computer was receiving surges of power. To add to this, the connected speaker made a loud noise at these intervals and this convinced me to flick the the powerswitch on the psu and turn it off. Following this, I deduced that the powersupply had gone bad possibly had damaged other pc components (I did not attempt to restart it).
-Today I tested the PSU and checked the voltages on the 24-pin motherboard connector and they all seemed fine. I powered the pc up with it and it would not post (no bios). The ram light was on so I tried using different sticks of ram and booting with just one stick of ram. None of this seemed to work. I verified that the sticks were in the right configuration via the motherboard manual and followed the procedure for using the ram reset button (mem ok button). According to the manual and the internet, the reset button was to be held until the light started blinking. This was supposed to reboot the system and begin "automatic memory tuning for successful boot". However this didn't work. No matter how long I pressed it the light never blinked and the memory tuning did not take place. I am confident at this point that at least one vital component is fried.

Miscellaneous Notes:
  • To determine if this was an overheating problem I previously downloaded HW Monitor to check temps. I ran the Unigine Heaven Benchmark and played some Planet Zoo, but never observed the temps getting to dangerous levels. The CPU idles at 24-30 C and the highest I saw it get to was 40-50 C. The GPU ran a little hotter and even got to 76 C, but that was nothing alarming as it was using the stock cooler and seems to have a reputation for getting a little hot.
  • As for wattage use the CPU and GPU both got to about 150 watts max so I don't think the 650 watt psu should have had any issues in this department.
-All the (5 case fans, one fan on cpu, two gpu fans, and psu fan) fans in the case are working and there are no major airflow blockages to components.
-I updated the bios to the most recent version yesterday to see if it would fix the problem and I am extremely certain that it had no effect on the outcome. It booted fine afterward and the issue was the same as it was before I updated the bios.

How can I test which components may have been destroyed and where do I go from here? Any help is appreciated.