Intel® Core™2 Duo Processor E6600 (4M Cache, 2.40 GHz, 1066 MHz FSB) Intel® Core™2 Duo Processor E6700 (4M Cache, 2.66 GHz, 1066 MHz FSB)

We have an old serial port device that will not communicate with it's software properly on an Optiplex 790/7010 running Windows 7 (Enterprise x64). On a Optiplex 755 running Windows 7 (enterprise x64) it works fine.

please can anyone help me resolved my issue about why my dell xps 8700 makes one initial beep then 5 beeps then no dell start up logo skips startup, no access to bios setting just black screen then windows startup appears normally.