delayed boot Old PC Delay on post

[Batiplayss]

I have a little problem, i tried to do some Undervolting to an AMD Athlon ii x4 635, i turned off the computer (without plugging off the rig), when i Push the Button, fans start to spin and the rig delays about 1 minute before starting to post 40 seconds when i turn the voltage back to stock, everything starts normally.

When i plug it off and back on it posts with no delay

 

This is my old rig

 

Motherboard GA-M68MT-S2P rev 3.0

Amd Athlon ii x4 635 2.9 ghz

2Gb Ram ddr3 1333 mhz (will be 6 later)

GT 710 1gb ddr3

Hard drive Sata 3 5700 rpm 500 gb

PSU Noganet (generic) 500w ATX

 

One thing to note is that the PSU is not presenting any visible malfunctioning or instability, and not much temperature when the rig is working at 100%