Computer doesn't turn on (a week after non use)

Hello,

I've just returned from a weeks holiday and I tried to turn my computer on but it fails to do so.

I left my computer as I normally do. I use it everyday usually, but returned to find it not working. The red light on the front of my case is on, indicating that there is power to the machine.

I opened my case and pressed the power button to see if anything happened. I noticed that my fan moved for half a second when I pressed the power button, but that is it.

I have unplugged the 24 pin and 4 pin cables that were plugged into my motherboard and plugged them back in.

Ive taken out the battery on the motherboard to restart the CMOS (I think it's called that) and put it back in. Doesn't work.

I have tested the computer's power cable with my monitor and that turns it on. I've tested the wall socket with a lamp, and the lamp works.

Any help please?!

Here's my spec.

• Gigabyte B75-MD3H
• Intel Core i7 (3770) 3.5GHz X 4 (14GHz) L2 Cache 8MB
• 8 x USBS Ports Onboard Raid 0/ Raid 1/ Raid 0+1
• 5.20 Internal Card Reader & High Definition Audio Surround Sound
• Network Fast Ethernet Gigabit Lan & Wireless Lan 802.11b/g/n
• Ram 8GB DDR3 Kingston Hyper X
• Display PCI Express NVIDIA Geforce GTX 660Ti 2048MB
• Hard Drive 500GB SATA II
• Windows 7 Home Premium 64bit