HP PRO 3400 Series MT

Hi All,

I need some help.

We have a HP PRO 3400 Series MT PC, when we add usb HUBS with GSM devices the system runs fine for about 3 hours, after this the screen goes black but you can still see the mouse cursor and the keyboard seems fine.

Its all fine with 3 HUBS and 21 gsm devices but more than that the system goes all wonky.

I hare replaced the CPU, PSU, RAM and motherboard with luck

6x USB 7 port hubs
42x gsm devices