Hey, its not too bad - I have an identical spare MB, and provided the Xeons and memory are ok, I can just fit them into this.. There are a number of possible hardware causes (I am fairly sure its not driver - the sound suddenly went dead while watching your video - this is not typical driver failure) - I cannot remember if, when I fitted the combo FW/USB card, I used the USB on this - I think I did, as the MB supported USB 1, and the card USB 2... In this case it is possible that this card is faulty.. But the fact that the soundcard died does indicate a MB fault.
But also, I have been having some strange simulation crashes over the last few days - Corrupt RAM could do this.. But also, the PC has problems powering up at times.. PSU ?
Oh hell - It could be anything! LOL ;-) ... In the past I would just buy a Reconditioned Dell (like this one is) for about £150 and dump the faulty PC in the loft, to sit on top of a load of other older Dells, IBM PC-AT's, Amstrad 1512's, Atari's, BBC Micro's, and probably even a couple of Sinclair ZX81's - I have enough junk there to start a museum! - Even have a complete CPM system with dual 8" Floppy drives and probably even the teletype I used for programming this ;-) .... Then I have a mountain of faulty synths and keyboards I bought for peanuts because they didntb work, or found at the dump, but never even got to examining fully, let alone fix!
But this time buying anything is off the cards, so its probably a day or so down the pan.. This PC has given me about 4 years of brilliant service, at £150 I cant complain.. I spend more on so-called long-life ECO light bulbs!
Fred.