Wake issues.

[CrossLOPER]

I frequently place my computer into standby to conserve power. After installing a new PSU, the computer now has issues with waking, where it will power up for a second and then cease. Pushing the power button is a wild card where it will either wake or just power down completely. The length of time it has been asleep appears to be a factor.

I updated the BIOS and loaded the defaults. It did not help. Should I clear the CMOS? The PSU seems to be handling heavy loads relatively well and the machine now responds immediately when I power it up instead of there being about a second of lag before the fans kick in. (compared to the PSU it replaced)

MB: Sabertooth P67 (this motherboard is known for the wake issue, but I thought I resolved it with a BIOS update a year ago)
PSU: Corsair HX750