The first two - probably a BIOS flash is the only option to induce a change in the MB device detection as it is. Otherwise it is likely individual chips/connectors are the culprit. BIOS updates for the next two, while also resetting to default settings. The 'chassis intrusion' message indicates a jumper may be improperly missing or installed on the MB connector. RAM + VGA (PCI or APG?) if integrated VGA exists, check for 1st initialzed device - PCI/AGP, check for IRQ assignment- many ATI (IIRC, older) cards don't need an IRQ. try a PCI video card, your (video-connector) slot may be bad, or not support the AGP 1x/2x/4x/8x card your installing. Resetting a BIOS to defaults may require you to poke into the nooks and crannies of the BIOS to check for settings. ESD issues can cause a setting to 'stick' in a BIOS, yank the battery and power then operate the power switch- (power led) should light up briefly as it burns any residual charge. Check for blown/leaking capacitors!!