Thanks for all the replies and the clarification. It is really helpful and appreciated.
So I set the CPU speed again in the BIOS to 2.083MHz ... CPU Freq. Multi. 12.5x ... CPU Ext. Freq. 166\33 ... Mem. Freq. 333 (also tried Auto) ... with just the PC2700 512mb module ... and the system still hangs. Same thing (hangs) with just the PC3200 512 module (same values as above in BIOS).
I put both modules back in with the PC2700 in the first RAM slot ... the PC3200 in the second RAM slot (that's the reverse order than yesterday's test) ... and with those same values above in BIOS it hangs.
So I left both modules as is and set the BIOS CPU speed to Manual ... CPU Freq. Multi. 12.5x ... CPU Ext. Freq. 133\33 ... Mem. Freq. 333 ... and the system doesn't hang (same as yesterday's test when set to Manual with those values in BIOS)
So when the system is running OK ... the ASUS Windows XP utility reports the CPU current speed as 1666MHz ... and the external clock as 133Mhz.
The max speed of the CPU should be around 2083MHz (I believe) ... so my current Manual BIOS settings ... that prevent the system from hanging ... are also forcing my CPU to under-perform. But as long as it's stable ... I'm happy for now. I need to decide what I want to do with this computer anyway.
I wish had some more RAM modules sitting around to test in this board.
UPDATE NOTE: I just found the ASUS A7V33-X manual that came with this board! It says "when using 333MHz FSB CPU (which is what I have) ... system memory supports DDR333 only". That implies that the PC3200 shouldn't even be working in this board ... correct!? Also says "PC2700 max. to 4 banks only" ... which I think means I can only put two PC2700 modules in the first two slots ... as I believe each slot is 2 banks ... correct? There are three RAM slots. So I find it odd that the one PC2700 512mb module hangs the system when it's in the first RAM slot (bank) and is DDR333 ... the same as the 333MHz FSB CPU ... seems like the PC2700 should support the CPU speed of 2083MHz when I set it as such in the BIOS. Oh ... and still no over-heating issues or voltage issues ... per the BIOS ... and per the ASUS Windows XP utility.
Sorry about the long confusing ramble. I'm still trying to wrap my head around this stuff 😀 Thanks for any explanations.