|"The monitor power indicator goes from BLUE to YELLOW during the freeze up, like it would if it's on standby."|
It isn't receiving a video signal during that time - that may or may not be be normal for that monitor. Black screening is not a normal situation for a freeze - that's almost always caused by a hardware problem.
Did you replace the PS before the original one started to fail, or after it started to fail, or after the original one died?
Have you had these freezes ever since replacing the power supply, or is this a more recent problem?
Thermaltake are better than average, but you should still check the voltages in the bios Setup screens - see the first link in response 1.
Something may be overheating.
Remove the power to your case. Make sure the cpu fan is clean, and the heatsink fan is clean, especially underneath the cpu fan (you may need to remove the fan).
If you have a chipset fan on the mboard, or a chipset fan on a video card, make sure they are clean.
Restore power to the case. Make sure the cpu fan is spinning. If you have a chipset fan on the mboard, or a chipset fan on a video card, make sure they are spinning. If any of the fans make any rattling or screeching sounds - that's more likely to show up when the computer is started up after the computer has cooled to room temp - they must be replaced. A cpu fan must be replaced as soon as you can.
Do the last two things in response 1, if you haven't already.
If the hard drive passes there are more things to try.