Enermax and P4P800 Won't Run

Is there some problem with Enermax psu's not working with the Asus P4P800? I just setup this board tonight and it would not power on with two different Enermax 350's. The board will power on for a split second and then power off. It won't do anything else until I pull the cord and plug it back in. Then it will repeat the same problem. At first I thought it had a short, so I pulled the board out of the case and tried it on a table with nothing hooked up except for cpu and ram. It still wouldn't power up so I tried a cheap allied unit and much to my surprise it powered up fine. I decided that particular enermax unit was dead, so I got a second one and it too exhibited the same problem. So as I type this the board is running normally with a cheapo 250 watt allied unit - which of course won't let me overclock I'm sure. I'm really puzzled by this one. Any ideas?

I think I had to plug in that 3 pin fan monitoring plug on the 350 PSU to the mobo for it to work.Actually it was the fan on the PS wouldn't spin with it not connected.I know when I forgot to plug in the P4 connector one time it light for a second and shut down,but I know you wouldn't have made that mistake..LOL.

Well one psu has the fan plug and the other doesn't, but neither one would work. I've never had a problem with either of these psu's, nor any other Enermax for that matter. By "P4 connector" I assume you mean the extra 4-pin power plug. I did connect that, as well as a fan to the cpu fan connector. Didn't make any difference. I'm trying to decide if I should buy a new psu, but what if a new one has the same problem....

Im running an enermax 431 and it runs fine. The asus board maybe really sensitive to 5v rail or something. I had that problem once to, but it was a short on the motherboard. I put an extra metal spacer in .

I use an enermax 350 with my p4p800 just fine.