i have a pentium celeron 400. compusa brand. computer boots but nothing shows up on the monitor. the monitor is fine. the cables are fine. it has onboard video that i cannot turn off. it makes all the normal booting sounds, but does not sound like it is going much further than the hard drive test. it has 1 ram chip in it, 1 hard drive, one floppy drive, and one cd rom. nothing else. am i forgetting something to get it to turn on and preform a normal boot?