Q: powermac g4 not working...

I can't get it to do anything, i've plugged the kb in all the slots (the kb works fine) including those in a usb 2.0 PCI card & it still doesn't respond to anything but the power button. I have also tried removing the card at startup. I'm starting to think its a PSU issue, as they are said to fail a lot in the MDD's, but they cost a bomb & it seems a bit strange as the previous owner used it frequently for design :/

It seems like a great idea but I intend on using the firewire ports a lot & want it to be 100% reliable, & if possible original, for the sake of resale value in the future. I also intend on putting it in sleep mode a lot too. I'll try some other things suggested by various internet sources, & would also be open to any other suggestions...

after watching this video:

https://www.youtube.com/watch?v=rbl90GHKNgU

the guy has exactly the same issue as me. the mac powers up, but emits no chime. the red LED indicator lights up, & after a few seconds the fan kicks in at full speed & doesn't die down. He somewhat explains the issue being a motherboard failure, which is now what I'm convinced the problem is. I might order this board from eBay, which is a pretty good deal:

http://www.ebay.co.uk/itm/Apple-PowerMac-G4-Mirror-Door-MDD-Logic-Board-630T-465 9-630-4655-1-25GHZ-/251895249646?pt=LH_D…

I can resell the extra RAM, single core CPU & heatsink... but before all that, are there any mac gurus who can help me confirm the issue?

hmm, theres a lot of stuff about the PSU's in these macs going out, especially the windtunnels... I might start off by replacing the PSU then if that doesn't work i'll return it & get the much more expensive & hard to find motherboard - is this a good option?

http://www.ebay.co.uk/itm/231024974062?_trksid=p2060353.m1438.l2648&ssPageName=S TRK%3AMEBIDX%3AIT

I think so... its underneath the card on the surface of the board which is held down by 2 screws, isn't it?

820 - 1500 - A

also says its a 2003 board.

I realised that nearly instantly after posting it, oops :/

the board thats up for £40 is probably what I'm going to go for (search results will change in the future for others referring to this forum). its refurbished too so thats even better. thanks for providing that search idea, I never thought of it

Sorry for not replying for such a long time, but things have since changed. Because it wouldn't have been cost effective to repair the PowerMac, on top of the fact that I didn't have much use for it anyway, I have since sold it for parts on eBay & have made back nearly all of what I spent on it. For anyone with the same problem in the future, I can guarantee the problem is the motherboard, since i've sold the other suspect, the power supply, to someone who says it works fine. Anyway, thank you very much BDAqua for helping out.