The warranty is not the be all and end all. PC's - like all other goods are expected to conform to reasonable use under the Sale of Goods Act. A complete failure after just one year for a PC is not reasonable use and you would have a claim against the SELLER of the machine on the grounds of
durability. See the information on the UK Trading Standards website click here
You can make a claim for up to six years after purchase if you believe the goods should have lasted that long. These rights supercede any warranty. Contact your local trading standards for advice. You could take action in the small claims court.