P5GD2 Premium cycles on boot

The setup is: P5GD2 Premium MB, Intel Pentium 4 540 3.2E GHz chip, ABIT RX600 PRO-128 PCIE graphics card, Kingston 512MB PC2-4200 memory

This system has started cycling on boot up. It gets about 10 seconds into the Windows logo, then reboots itself. It WILL boot up in SAFE mode, and SAFE MODE WITH NETWORKING. It will NOT clean boot, or boot with all services and startup programs disabled using msconfig. It will NOT boot in diagnostic mode.

I have disabled all on-board devices and pulled all external cards except for the graphics card - still it cycles.

I don't know what to try next other than a new MB. Any ideas out there?