New PSU comp won't boot? Cause??

[Ferra]

I just got an Antec Neo Eco 450C, went home to hook it up on my PC but it won't boot up. (no post, black screen, lights and fans on)
sys spec:
Phenom X4 965
8GB Ram
WD 640GB Black
EVGA GTX460

I have a OCZ 500w PSU on the PC right now which is working fine....any idea as to why the antec won't boot up? Is the 450w PSU not providing enough power?
(I have a power meter, the system never draws >260w even when gaming heavily)

The other thing is, the OCZ psu has 2 PCI-E cable that can connects to the video card, while the Antec 450C only has one. However, the PC will still boot if i use only 1 PCI-E cable with the OCZ PSU.

And the Antec 450c has a 4+4 pin ATX/EPS, where else the OCZ uses just one 8pin connectors to connect the mobo.

FYI: I wanted to use the Antec Neo Eco 450C because the OCZ PSU is very noisy...it is noticeably louder than the cpu/case/video card fans.

[roastpuff]

Make sure all the connections are tight... take them off and re-seat the main power connector. That's my guess to the culprit if it doesn't post.