Dimension L1000R motherboard or processor
the dimension l1000r does not have a standard power supply. it does have a standard power connector but it is wired differently than a generic power supply. fortunately (and probably deliberately) it was designed so that no harm would come to your system by accidentally installing a generic supply; it simply won't work. now that you have your dell power supply back in your system try booting the machine and then look on the back of the system for the four leds labeled a-b-c-d. they will either lite green or yellow in a pattern that indicates an error code that can be looked up at support.dell.com or you can post your findings here. since your machine came with an integrated video card you problem may simply be having the monitor plugged into a add on video card that was installed in one of the expansion slots (sometimes this results in not seeing the start up screens which can clue you into the problem). tell us more before we speculate any further...
Is a Labreastude C640 USB 1.x or USB 2.0
Also, I'm wondering about the USB speeds on the C-Dock-II and C-Port-2 docking stations and port replicators ? I've suspected that the difference...