PC does not SLEEP, what can i do?

Like title PC doesn't sleep. It goes into sleep mode and immediately wakes itself up without me provoking it.
Its been very annoying lately as I've been trying to find the cause and a fix.
PC is custom built running WIN 7 x64, with a water cooler. I've disabled the option to allow any USB devices to wake computer, as well as Mice, Keyboard, and Internet via Device manager.

I've narrowed down the cause to be the Water cooler, its powered through a USB that connects to the back of the PC. once i disconnect it the computer finally sleeps and stays asleep
how can i fix this and allow the pc to fall alseep? +1,000 Internetz points to anyone that can help me

Try these tutorials, may or may not help with your issue.

https://www.sevenforums.com/tutorials/122012-lastwake-command.html
http://www.vistax64.com/tutorials/63567-power-options-sleep-mode-problems.html

Hope this helps,
John

Can you find a USB device under "USB Serial Device Controllers" in Device Manager that you know is the water cooler?

One way to find it would be to look at all the devices listed with the cooler disconnected from the USB port and then see what pops up when you plug it in or out.

If you find it, see if there is a setting to keep it from waking the PC there.

Corsair systems plug into one of the USB 2.0 blocks on the motherboard. Are you saying that yours plugs into a normal USB port on the back on the PC - the wire comes out of the case?
Good to know the Brand & Model of that unit.