Facing problems sometimes when turning on my PC

[Lawk Duski]

Hello
Sometimes. when i turn on my PC (by the I/O Button on the Case) it turns on but literally nothing works. only 120mm fans (which are connected to PSU). my Motherboard has an LED that is on but yet again that LED is 24/7 on even if the PC is turned off. but like i said. GPU doesnt work. CPU Doesnt work. dont hear my HDD ticking. only i hear the sound of 120mm fans. and even Case's HDD and power LED dont turn on. this happens ONLY sometimes when i turn on my pc, then i cut the power then turn it back on and it works all good. any clue whats the problem?
im kinda guessing its my PSU. my PSU Is Corsair CX600

 

[S15557]

What are your specifications? Is the 24 pin connector plugged in your motherboard properly?

 

[smorizio]

sounds like a bad cap in the rig. one that not charging or powering on right at first power up. on the second and after the cap or part is fine. if it not a cap is may be power good line on the power supply or the mb.

 

[Lawk Duski]

What are your specifications? Is the 24 pin connector plugged in your motherboard properly?

my specs are
i5 4690k
8GB Crucial 1600mhz ram (2 4gb sticks)
Asus Z97-E Motherboard
500GB WD Blue HDD
Cooler master K280 Case
Corsair CX 600 PSU
Asus Radeon HD 7850 DCU2 GDDR5 V2 gpu

i THINK my 24 pin connector is fine. even through when i first built my rig i had a bit of problem plugging the 24 pin in. but i managed to connect it anyway

 

[S15557]

PSU seems good enough to power all that, so its only the fans that spin right?

 

[Lawk Duski]

PSU seems good enough to power all that, so its only the fans that spin right?

yep

 

[S15557]

Do you hear anything else, I've never came across this type of problem.