Games Crashing; Possibly Overheat or PSU Issue?

Question

I've been grappling with this problem for a couple weeks, and I think I've narrowed it down to either an overheating or power supply issue.
I get system crashes while playing games.  I've never had a crash in 2-D mode.  I only have three games installed right now - Battlefield 1942, Call of Duty and IL-2:FB/AEP.
I installed SpeedFan last night and configured it to display my CPU temp in the system tray.  At idle it is running at 40-41.  I then started up Call of Duty singleplayer.  Within 20 seconds of starting the game, the CPU temp jumped to 52.   As I continued to play, the temp gradually rose to hover at 55-56.  It leveled out at this temperature for about 15 minutes, then it locked up.  I rebooted and immediately went back into the game, and this time it locked up after about 15 seconds.  I tried again and it locked after 15 seconds or so again.  IL-2 locks after anywhere from 10 to 45 minutes, with no apparent pattern.  Battlefield 1942 only locks after a long time, 2 hours or so.  Since I don't usually play this game for such a long time, BF1942 hasn't crashed in a while.
When a crash occurs, the video and sound both stop completely.  There's an annoying buzzing sound from the speakers.  Keyboard and mouse are unresponsive.  I have to press the power button to solve it.
I've tried updating video and sound card drivers, reinstalling DX9, lowering hardware sound acceleration to standard instead of full in DX9, changing display resolutions both in Display Properties and in each game, and just about everything else I know to do.
Here's my specs:
Intel Pentium 4 2.8GHz HTT w/ 800MHz FSB
MSI 856PE Neo2-P mobo chipset (unsure of BIOS version, don't know how to check)
1GB Kingston PC3200 DDR RAM @ 400MHz (2x512MB sticks)
Maxtor 6Y120M0 120GB HDD
Diamond Viper Radeon 9600XT 256MB (Catalyst 4.9s)
Creative SB Live 5.1 (latest drivers)
Ultra ATX Switching PSU 400W, Model #WIN-400PS
+3.3V = 15.0A
+5V = 30.0A
+12V = 17.0
-5V = 0.6A
-12V = 0.6A
+5VSB = 2.0A
At first I thought it was a problem with the CPU overheating.  I posted this problem on another forum and someone replied saying that P4s shouldn't even be getting into the 50C degree range.  Then I came on here and read about people's Prescotts running at 70 or even 80C.  Even under heavy load, I've never seen my temp reading go past 57.  I have two 120mm rear case fans which both run at max RPM all the time, and another in the side of the case.  The CPU fan runs at high RPM all the time as well.  Multiple programs show minimal case temperature increases under load.  The video card has no heat sensor, but there are two free PCI slots below it, so there is plenty of breathing room.  I have the case off and a house fan blowing directly into the case and across the video card.
I read something saying that 20 or 21A was required on the "12V strip" or something like that (sorry if I butchered the terminology, I am new to this technical hardware deal).  According to the label on the PSU, it is supplying 17A @ 12V.
I have Speedfan, Motherboard Monitor 5, Sisoft Sandra and Everest Home Edition installed, so I can give outputs from those programs if needed, assuming someone tells me how.
Sorry if I screwed up royally and didn't give the correct information, today is the first time I've ever read this forum.
Thanks in advance for any help.
EDIT:  I read in another thread here where someone had a similarly unstable system, and someone said to go into the BIOS and change the "RAM voltage" (sorry again for possible butchering) or somesuch from the default 2.5 to 2.65 or above. I went into my BIOS and found such a setting.  Mine was set on 2.6.  The only option it gave me to change to was 3.00V.  There was a warning message on the right side saying values in white were safe values, yellow were high-performance, and red were unrecommended settings possibly resulting in system instability.  I switched it to 3.00V just to see what it would do, but it was listed in red, so I went back to 2.60.

Answer 1

Quote
Originally posted by Danny
In order these would be my choices from that site:
http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=923509&CatId=1078
http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=923508&CatId=1078
Go to Enermax's web site for spec's. These people didn't copy them correctly.
I'm a bit wary about the dual 12V rails that these PSUs have.  I went to the Enermax website and it lists each rail seperately, one is 16A and the other is 15A.  They'll both be used at the same time, right?  Because if not, they'll be supplying even less power than my current one, and will make my crashing problem even worse.
From the Enermax website:
Quote
Independent 12V rails supply to MB/CPU and drives in order to provide stable and clean current to noise-sensitive devices, such as: CPU, add-on cards.Meet UL 240VA safety requirements
I just want to make sure this thing will work correctly before I place the order.  Also, is there a special installation procedure for dual rails?  I probably won't be doing it myself, but will be getting an experienced computer person from on-campus tech support to help me out.