Re: Dell Optiplex GX150 won't boot up.

The OptiPlex GX150 is really old, if the hardware has failed its likely not worth the price in sourcing spare parts to fix your machine. You should instead get a new or used machine. Is there any reason you "need" this computer. Is it running legacy programs or connected to legacy hardware such a scientific instrument?

If you need an OptiPlex GX150 in particular you can buy the full unit for ~ $50 on eBay:

http://www.ebay.com/itm/Dell-Optiplex-GX150-Pentium-III-1-GHz-256-MB-20-GB-HD-/171034400809?pt=Desktop_PCs&hash=item27d271d829

Probably you can swap the hardware for the one you've got unless its failed also.

However you can also get a used Optiplex GX260 or GX280 for that price which are more powerful. Note Windows XP reaches its End of Life in less than a year so its not recommended to use legacy hardware and Windows XP unless you really have to see Windows XP SP3 and Office 2003 - End of Life April 2014.

It is recommended to get a machine with Windows 7, if you are on a budget look for a used OptiPlex 745, 755 or 760 with Windows 7:

http://www.ebay.com/sch/i.html?_odkw=optiplex+760&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR11.TRC1&_nkw=optiplex+760+windows+7&_sacat=0

http://www.ebay.com/sch/i.html?_odkw=optiplex+755+windows+7&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR0.TRC0&_nkw=optiplex+755+windows+7&_sacat=0 

http://www.ebay.com/sch/i.html?_odkw=optiplex+755+windows+7&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR0.TRC0&_nkw=optiplex+745+windows+7&_sacat=0 

Also direct from Dell - used OptiPlex Auctions:

http://www.dellauction.com/cgi-bin/ncommerce3/CategoryDisplay?cgrfnbr=75406108&cgmenbr=75267554&noMoreSubs=N