Blank screen on start up - Microsoft Windows XP Professional

Hi

You say there is a blank screen at Start Up. You do not say if the computer boots successfully into the XP Operating System. Do you see the power LED and the Hard Drive Activity LED working? Can you see/hear the Hard Drive spinning? Ok. Try to eliminate the possibilities, one-by-one. I will assume, since you upgraded the PSU, that you have had the case open and therefore know if dust, dirt and grime would have clogged up the inside of the computer reducing its cooling efficiency and causing it to overheat. If you have not done so already, carefully use a vacuum cleaner with a narrow nozzle attachment.

Make sure the Front Panel Control Header Pins are fitted in the correct orientation.
Make sure the CPU and Heatsink are fitted correctly.
Make sure the CPU fan is connected.
Make sure the RAM is properly in the RAM slots.
Make sure the Graphics Card and any other PCI cards are properly in their slots.

Connect only the CPU Power Cable, the Hard Drive power cable and any Graphics card power cable (if you have a separate Graphics Card and it has a power connector) and, leaving the computer open and flat on the floor so you can see all parts inside, test the computer again.
If it works, shut the computer down; add the CD/DVD drive power cable, and then the case fans, testing as you add each extra device. Upgrade to a 550W PSU if you experience any failure or slow spinning of fans with the 300W PSU. After installing the new PSU, clear the BIOS by disconnecting the power cable and removing the small, silver CMOS battery for 2 minutes and then reinstalling it and then restarting the computer. If the computer boots, you could consider a BIOS update.

A well-ventilated desktop computer base unit has a fan arrangement that sucks in cooling air from a small open slot under the bottom edge of the front control panel and vents hot air extracted from the CPU and generated by most of the internal devices, via (an) extractor fan(s) at the rear. Choosing a good quality, efficient , low noise, large-bladed, multi fan PSU that sucks hot air in from multiple faces and vents in all out via a powerful, efficient, low, noise extractor fan on its rear face. A cheap PSU is a very false economy and worth spending a little extra in return for a disproportionate payoff in terms of cooling, performance and system stability.

Sometimes, positioning the base unit directly on a carpet with a thick shaggy pile, or enclosing in it, during use in a poorly ventilated under desk cubby hole, next to a radiator, or in place receiving direct sunlight, polarised by glass in the nearby windows or some similar place can have a underestimated impact on the base unit's ability to cool itself when in use. Cooling is essential for the CPU, Motherboard Chipset, Graphics Card or onboard Graphics Chip, Hard Drive and RAM Memory. All need to be as cool as possible to work at optimum efficiency and the performance of each suffers drastically when exposed to over hot conditions, particularly the CPU which, from stone cold, can reach the temperature of boiling water within seconds of the computer being powered up and will underperform, overheat and shut down at the merest incidence of over hot conditions.

So review all the salient cooling issues, then consider adding a separate, dedicated, fan cooled graphics card, its GPU Fan adding to the efficient cross circulation of cooling air to more of the interior and, also, its own built-in GRAM freeing up the 16Mb, 32Mb, 128Mb or 256Mb of System RAM that the on-board graphics chip borrowed from the RAM Modules. RAM that has to work less hard, works at a cooler temperature and thus more efficiently. The CPU works more efficiently as it no longer has to compensate as much for the loss of System RAM previously commandeered by the on board graphics, so it also generates less heat in doing so.


Consider also Inexpensive but beneficial, cooling Motherboard Chip and RAM Heat Sinks for the RAM Modules. Inexpensive, underside fan powered Hard Drive Coolers that screw to the underside of Hard Drives. See examples here:

http://www.amazon.com/Thermaltake-TMG-HD1-HDD-Cooler/dp/B000ZM8D4I/ref=sr_1_1?s=electronics&ie=UTF8&qid=1315115079&sr=1-1

http://www.amazon.com/Zalman-VGA-Ram-Heatsinks-ZM-RS1/dp/B0009YIJ2I/ref=sr_1_3?s=electronics&ie=UTF8&qid=1315114910&sr=1-3

http://www.amazon.com/gp/customer-media/product-gallery/B0009YIJ2I/ref=cm_ciu_pdp_images_3?ie=UTF8&index=3

The 550W PSU is necessitated by the extra cooling devices you contemplate installing

If none of the above works, then the Motherboard might either have a BIOS corruption or a power management fault.

A new motherboard might be obtainable from Dell but the price is likely to be prohibitive. Dell often have unique design architecture in their cases that makes it difficult or impossible to install other brands of comparable specification Motherboard.

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