That's only true of older/cheaper group regulated units. Newer/better PSUs derive +3.3V and +5V from a DC to DC buck converter coming off the +12V, so "dummy loading" the non-primary rails is not necessary.
I use hwinfo64 on background logging all my hardware while I use 3dmarks firestrike
Any component that is no longer in production costs more than the ones that are in production. See DDR2 or DDR3 Ram for example. They cost more now than what they used to have.
I would suggest to use a dual kit of RAM that was sold together to make sure perfect compatibility. Mix and match in RAMs is bad idea.