Strictly anecdotal, but I had a crazy problem with a SmartPower 500W. The computer (AMD A64 on a DFI Lanparty UT3 250GB) booted fine, but it couldn't see the onboard NIC. I thought the NIC was dead. Went out and bought a PCI Intel NIC and installed that. No boot after installation. OKAY. WTH is goin on here? Turns out it was a flakey PS. I had a spare 350W laying around and put that in. Bingo. It worked.
Not one of Antec's best. OTOH, my True Power Trio 650W is perfect. Of course, that's a Seasonic. Don't know if Seasonic makes the Smart Powers.