PC doesn't turn on immediately after shutting down

I just recently built a PC and everything seems to be working well, except this. Every time I shut down my PC and try to turn it back on again, it doesn't work. I have to disconnect the power from it and reconnect it before it will turn on. Restarting the computer, however, works perfectly fine (like for Windows Update).

Specs:

Motherboard: Z87X-UD3H Intel 1150

CPU: i7 4770k (no OC)

HDD: WD Caviar Blue 1TB

SSD: Kingston SSDNow V300 Series 120GB

GPU: MSI R9 280x

PSU: Corsair RM750

I guess those are the only parts that could hold some relevance to this topic. If there are other parts that I should list, let me know, please. Thank you!

Try reconnection the front panel connectors?

Just like skullabyss said, the connector for the power button might be loose or something along those lines.

Have you tried the usual fix's?, resetting the CMOS/BIOS and making sure stuff like wake on lan/wan etc is disabled?

Ive had this issue before a long time ago and it turned out to be a bad PSU (had a bad cutout), also try it with a different kettle lead, it may help.

Its the PSU, mine used to do the same thing. Takes time for the caps to discharge and whatnot.