Computer boot problems, fan spins then stops (works after jiggling wires, see post for info).

[TELK]

Hi, I've got some problems with my computer. I have the classic "press the power button, computer fan spins, then stops, then spins... and so on" problem.
This is not a new build (over 3,5 years old). I have tried the trouble shooting sticky on these forums. I also did the paperclip test on my PSU, and it works as it should.

After detaching and then reattaching all powercables it worked again.

Yesterday, same problem. But after I disconnected the power cable from the motherboard (and the four pin connector), then reattached them, it worked again. So, faulty wires? Loose cables? Messed up hardware? It's troublesome if this keeps happening.

OS: Windows 7 Ultimate

Specs:

Processor: Intel Core i5 2500k

Video: Gainward GTX 970

Motherboard: Gigabyte GA-Z68AP-D3

Memory: Kingston HyperX 1600MHz 8GB

Hard Drive: Seagate Barracuda® 7200.12 1TB

SSD: 64GB Crucial m4

Cooler: Arctic Cooling Freezer 13 Pro

Optical Drive: Samsung SH-S222AB

Power Supply: OCZ ModXStream 700W

Thanks in advance for all help and tips!

 

[popatim]

How did you verify the PSU works as it should?

 

[TELK]

How did you verify the PSU works as it should?

I only verified it through performing the paperclip test (http://www.wikihow.com/Check-a-Power-Supply). I'm guessing that is not sufficient? I don't have a multimeter on hand, should I perform some other tests?

After turning of the computer last night the problem occurred again today. I've not changed anything about it since yesterday.