No Power on- Power Supply is good. Computer was LITERALLY just working

[Dieselroar]

Okay, first here are my specs

Antec Truepower 430w
DFI P45-T2RS
Intel E5200
ATI 4850 512mb
4gb OCZ Reaper DDR2800
Fans+Watercooling setup
250gb Seagate
Blu-ray drive

Here's my situation:

My original Power supply, an OCZ 500w modular, broke 2 days ago. I just borrowed my friends antec while waiting for an RMA. I powered up my computer using the Antec and everything was fine. (The wattage is REALLY close but the antec has good amps so I guess it's enough). I used my computer for a few hours then put it to sleep. Later, I came home and turned off my computer. I then tried to turn it back ON and nothing happened...sooo...wtf basically. One other thing: I have a standby light on but the DRAM motherboard Power LED is NOT on so for some reason I'm guessing my motherboard just isn't getting power...

Here's what I've done so far:

I have tested the power Supply. (working)
I have checked all power and Data connections (correct and secure)
I have removed PCIE cable to ensure it's not a problem of insufficient power (didn't help)
I have removed one and then both memory modules (nothing)
I have removed ALL cables from the back of the case.
I have hit my head against my desk (painful and unhelpful)

Does anyone have any ideas?

again; my computer was WORKING then I turned it OFF and now it WONT turn on. I get NO sounds NO Fans NO NOTHING.

Thanks for any and all help.

 

[r_manic]

How did you test the power supply? Did you try another power supply with your system?

 

[Dieselroar]

I used a power supply tester first then I used a paper clip to run the watercooling the lights and the fans alone.