I'll jump straight to my query- Could a faulty PSU cause a system to hang at the splash screen?
Here's the details:
I've been testing this system for the better part of the week. To say it's unstable is an understatement. Originally the issue was a failure to boot to the desktop. It's a Cyberpower PC with Win7, 320 Gb HDD, 4Gb DDR3, Athlon II X2 255, and a Geforce GT 640 videocard. More on the videocard in a moment...
POST takes a long time to load. I count approx. 6 seconds before you get a beep, then the POST screen takes about twice that before it goes to boot.
As I mentioned, the system would hang on the splash screen. Booting to safe mode would hang on a black screen. Attempts to boot with a CD or USB would fail- it would not recognize either. Startup Repair initially would boot to a black screen, later it would crash/reboot.
I removed the video card and got the system to boot to Safe mode, while still hanging in Normal mode. There was a lot of malware infecting the system, so I removed the hard drive and loaded it into a testing PC and ran MBAM and Adwcleaner.
Reinstalled the hard drive and it booted to Normal mode without any issues. Did some more cleanup (removed Regback Registry Cleaner, CCleaner, Linksicle adware), ran Startup Repair, ran chkdsk from command prompt 3 times (fixed errors). Still worked fine.
I reinstalled the video card and on the second test boot the PC hung on the splash screen again. Now, the videocard was installed long after the initial purchase (PC was purchased in 2010, videocard in 2012) so I suspected the videocard, but could not find any issue with it.
We had just received a shipment of new PSUs so I tried one on the PC. With the new PSU, the boot was so fast that the first thing I see (when the CRT monitor gets going) is the splash screen. In all the boot time is 1/3 of what it was with the old PSU.
To further test, I reattached the old PSU and it booted fine several times. Then I did a hard reset (flipped the switch on the PSU) and it started hanging on the splash screen again. Reinstalled the new PSU and it started working fine.
So the question remains- Is the PSU causing the issue? May be a stupid question, but it seems like every time I think it's fixed, it throws me another wrench.