hey mate, its been awhile since i used these but i got the matrox th2g digital edition (vga & dvi in, 3x dvi out) and digital se (dp in, 3x dvi out) and if i remember correctly both have power status leds. Red for stand by and green for power on. If the th2g unit is NOT showing red then i suspect you may have a dud usb power cable or port on the computer. If the led shows green but the monitors are going to sleep (no signal) then maybe the default resolution of the dell monitors are not supported out of the box from the matrox th2g unit and you will need to install powerdesk (matrox software) to get custom res support. This is especially so for the digital edition unit. Its still possible you might have a dud unit but double check your hardware and software before spending coin. I hope this helps in some way. Also if you do need to get new hardware then another th2g company is called mview (
http://www.mviewtech.com/class_en.asp?catid=829) but these days upgrading your video card is probably cheaper, for example a Radeon 7770 can do 3 monitors out of the box:
http://www.sapphiretech.com/presentatio ... 1723&lid=1(Im sure there are other better cards but doing some reaserch into this will yeild better results than a th2g unit)