Computer does not start

[Jaspervd]

CPU: INTEL COREI5 3350P 3.1G 6MB BOX
RAM: Corsair 8GB PC3-12800 Vengeance Low Profile DDR3 SDRAM (2x 4GB, 1600MHz, CL9)
GPU: Club3D ATI Radeon HD7850 1GB DDR5 Royal King Edition (PCI-e)
MOBO: ASRock B75 Pro3-M (Socket 1155)
SSD: Samsung 64GB Solid State 830 Series (SATA-600, 2.5" )
HDD: Seagate 500GB Barracuda 7200 (SATA-600, 3.5" )
Power: Corsair 430W CX Bronze Series V3

I'm trying to build my first computer, after installing everything:

When I press the on button, the power led goes green, but the light immediately fades out.
-No beeps
-fans moving
-I have already tried disconnecting various parts (ram, ssd, hdd) to find the cause, but so far no succes!

I think I have located the problem:

My 24ATX cable won't connect for a 100% like it should:

I have tried the 24ATX cable on a different mobo and the same problem occurs, the cable won't go in a 100%
I have tried connecting a 20ATX cable of an old power supply to the mobo and that cable connects just fine.

My question is could I connect my old power supply (200 watt, 20ATX) to my new computer, just to test if this is indeed the problem. I don't want to ruin my new computer because the old power supply doesn't have enough watt (if that is possible)

 

[suteck]

Do you have it turned the wright way? Is it binding on the +4 pin? Is the 4 pin turned the wright way? Do you have the 2 parts put together when you plug it in? That's usually the best way to make the connection. Do you have the other 8 pin motherboard connector plugged in? Dumb questions I know, but I gotta ask.

As for using the 200watt? it won't hurt. But you will have to have the other +4 pin, and, all you will be able to find out is if it stays on. Don't forget, without the other 8 pin (you can probably get away with using a 4 pin connector there just for power-on testing) it probably won't boot anyway, it needs that power for the cpu. But you will have to use a jumper wire in the new psu to power the video card.

Look real hard at the power plug and at the connectors. They are actually shaped to go in only one way as different corners are shaped differently to it won't actually go in the wrong way without being forced.

 

[Jaspervd]

I have managed to get the ATX24 in after some hassle, the other 8 pin and GPU are also connected.

this didn't change anything though, it still won't startup.


Maybe there is something wrong with the way how I connected the front of the computer case with my motherboard?

(on the left: the cables coming out of my case, on the right: lay-out according to the motherboard manual and underneath what i did)

 

[suteck]

It looks correct to me. Don't you have a reset switch though? Try this - unplug all those wires and put a screwdriver across the two power pins and see if it comes on. All that other stuff are just lights. Just need to touch them for a second and it should come on. Turn the power switch off to turn it off. this will confirm or disprove the power switch wires causing the problem.