just as an update...
the old pcp&p psu that was a possible culprit in this issue turned out to not work all that well when paired back with the original motherboard and a pci 6200 graphics card. it worked for a short time, then the system wouldn't start up, giving constant beeps... looks like it did give up the ghost for good.
also the mushkin ddr3 essentials kit went back to mushkin, and they sent me two new sticks to replace the bad. i haven't tested them yet in any machine, but i trust mushkin did me right.
my main rig...
asrock 970 extreme3
AMD athlonII X3 440
zalman cpns5x performa hs/fan
crucial ballistix 2x4gb sport ddr3-1333
powercolor ax7750 1GBK3-H vga
antec neo he 650r
Samsung 840 EVo SSD 120 GB
toshiba 2TB HDD 64M cache sata3
seagate 1TB HDD 64M cache sata3
hitachi 2TB HDD 64M cache sata3
lg wh14ns40 bd burner
optiarc ad-7240s sata dvdrw (nec chipset)