I also bought a P150 at Fry's and while I had trouble with my Gigabyte K8NS ultra 939 motherboard, it now appears that it was not related to the NEO HE 430.
Thanks for the info, GB. Well, I've been busy since midday when I posted previously.
The summary is that I'm inclined to blame the intel motherboard more than any other single component. It looks to me like there is something about the 12v supply on these power supplies that doesn't satisfy the intel mobo (see above for the exact model I had), so that when the issue occurs, they won't attempt to boot up. Perhaps my home office voltage is slightly low, etc. etc. Remember, I tried four power supplies with the offending mobo, and 3/4 didn't work (all were Antec, the oldest worked - see above for exact model).
I kept the P150 case, which I like (power supply level A04, though it didn't work with my intel mobo), and exchanged the intel mobo for an Asus P5NSLI mobo. It works flawlessly with the P150 / NEO PS (so far, anyway).
Interestingly, there was an Intel rep working the mobo area at Frys when I made the exchange. He indicated that they (the reps) were informed of previous problems with this PS/mobo combination, but he thought it had all been resolved. I conclude (with sufficient precision for current personal satisfaction) that the Intel mobo that I had was more sensitive to PS voltage (or something else) than most other boards.
I hope you dont' have any trouble with your board. If I were you I would keep a different kind of spare power supply onhand, just in case. Heck, even as me, I bought a non-Antec power supply as a spare.
One postscript - I had one other complaint about the intel mobo: it's builtin graphics are not yet supported by Fedora Core 5 (linus). That install went catatonic when it tried to go graphical. Having said that, the Asus board doesn't have graphics builtin, so either way I needed a $50 card wtih a Geforce chipset...
Good night and good luck,