New
#101
Was this the first PC you built? Did you check all the connections again, if necessary rebuild it?
You cannot ever expect Win7 to start on different hardware. If it does, or if you correctly adjust it to do so, then you must be connected to the internet to swap out all drivers, with Hardware Auto-Updating enabled. You said neither of these was the case. You could either have bad drivers or the build is defective.
One way to test this is to run with a boot disk like Peppermint3 - Create Live CD/DVD/USB To Use For Emergency Backup - Windows 7 Forums with the hard drive unplugged to eliminate it and Win7 as involved with the results.
But you are badly in need of a perfect Clean Reinstall Windows 7. I don't know why you would build a new PC and then think that the OS is so unimportant it can be slapped on there from a laptop without adjustment. The OS is crucial and should be installed with the utmost care to assure it will work perfectly. So if you do reinstall don't waste the opportunity to follow the steps in that tutorial closely without missing any this time. Those steps are based on what has worked best in tens of thousands of installs we've directly helped with here since beta, and has been used by a million consumers without a single complaint or return here with problems if they stick with the tools and methods given.
If a boot disk and reinstall persist with the problem then we need to have our hardware experts help you tear down the build and rebuild it making sure nothing is done wrong.