Currently, this hardware device is not connected to the computer. (Code 45) Recommended resolution
This error occurs if a device that was previously connected to the computer is no longer connected. To resolve this problem, reconnect this hardware device to the computer.
No resolution is necessary. This error code is only used to indicate the disconnected status of the device and does not require you to resolve it. The error code resolves automatically when you connect the associated device to the computer
The following information is for the advanced user.
If Device Manager is started with the environment variable DEVMGR_SHOW_NONPRESENT_DEVICES set to 1
(which means show these devices), any previously attached (NONPRESENT) devices are displayed in the device list and assigned this error code. Explanation of error codes generated by Device Manager in Windows XP Professional
I would check to see if your connections are correct and reconnect and also have you adequate power supply - PSU - I just looked at your system specs and a 750w should be OK - maybe the watercooling is using too much power - seems you would know, just a suggestion.