System extremely unstable with stock clock

I'm having a weird issue with my computer, its completely unstable with stock cpu settings. The issue seemed to have started yesterday, after I updated my usb 3 driver. None of my usb devices would be recognized by windows, when I was actually able to get into windows for the view seconds I had, and windows would nonstop randomly restart. It even got so bad that when windows would try to start (it wouldnt even show the windows logo), it would just go through the entire boot process all over again. After multiple failed attempts at trying to get the usb 3.0 driver to revert (my keyboard and mouse were not being detected in windows+everything else I described, and at the time I suspected it to be a driver issue), I finally called quits and did a clean windows installation (Lucky I didnt have anything important, and most of my data is on my 2nd hard drive anyways). Once windows boots, everything seems fine and dandy, and I get all the software and drivers I need installed just fine. Then after about 30 minutes or so, I get the BSOD error 124 out of nowhere. Then I try to reboot a few times, same error instantly (I did get a different error code once, it was BSOD error 01). Based on my experience with overclocking (my cpu was not overclocked at all during this time, so its not an overclocking error), I came up with the insane Idea of downclocking my cpu from stock to 2.5GHz, because error 124 generally means you need more vcore and downclocking would result in the cpu needing less voltage. After downclocking to 2.5GHz, my computer seems stable, however I do not want my cpu to be running at less than stock speed. I think the problem might be my PSU as it is the oldest component in my computer (5+ years) and that it might not be able to provide the voltage the cpu needs at the stock 3.5Ghz speed, however I would like to hear your guys thoughts on this. My computer specs are:

CPU: Intel I5 4690k
GPU: AMD R9 290x (2)
PSU: Ultra x3 1600w
Motherboard: MSI Gaming GD65 Z97
Operating System: Windows 7 Pro
Ram: Mushkin Redline 8GB
SSD: Mushkin Chronos 240GB
HDD: Seagate Barracuda 2TB
Cooling Method: Water

Update: Ok, so I have reset the clock to stock and set the voltage to 1.25V, and it seems fine. So I guess the motherboard was undervolting the cpu too much when it was on auto voltage?