AlphaServer 1000a troubles

Hello all, This is a slightly modified version of the message that I've posted to comp.os.vms. Wanted to see if anyone here might have an idea. I'm trying to prepare an old AlphaServer 1000a with installed video card for an installation of VMS or Tru64. The difficulty starts when I turn it on. Sometimes the LCD on the front is active and displays the self tests and beeps once. More often than not, however, it remains blank and there is no beep. When the LCD _does_ turn on, the blue SRM console appears _temporarily_ some moments later on the monitor. For example, I notice that the tests have been successful and the machine gives me the ">>>" prompt. Then, about 1 min later, the screen goes dark -- even if I'm in the middle of typing something! Any ideas? Thanks, - Alex