I have a custom built computer with a new power supply but the computer will still not power up
No system specs given, no power supply info & you asked no questions.
like jam said.. we need information. are you getting lights at all? I'm assuming you are talking about the PSU and not a power cable?
Front power switch connected to the right pins on the board? 4/8-pin CPU power plugged in? CLR_CMOS jumper caps in the right place? CPU cooler properly attached? How about the RAM? I'm bouncing all over the place because, as the other two posters mentioned, you really need to give us more info.
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