i live in UK, and bought my self a CPU in my home country Philippines to use in here in UK since it's a bit cheaper to buy components and assemble them there than here, and it's working fine i even tested it, i knew about the Voltage~thingy in the Phil. 220v and in UK 110v so i bought my self a converter/transformer for it, but now the CPU keeps turning off on its own and the monitor is blank.

Your cpu is probably overheating, is the heat sink put on properly? Might want to inspect it to see if it is loose.

Did you actually mean the PC is shutting down ??? It could be the CPU overheating, but many other factors should be taken into consideration, maybe buy a UK PSU ??

I thought that the UK was also on the 220v system. Anyway, the AC voltage doesn't matter to a CPU, since it grabs its juice from the power supply after it's been converted from 110/220 VAC to 12 VDC. You could buy a CPU from anywhere in the world and plug in to your motherboard without frying it. Chances are good that when you upgraded the CPU you either forgot to apply fresh new themal grease to the new CPU, or incorrectly installed the heatsink. An overheating CPU will shut off in seconds.