My motherboard powers but it cannot load the bios screen? what's the problem?

Bios set up is done by stopping windows loading when you first power up and thus getting on the motherboard screen. It's often the F10 key to get on that screen, but it can vary. Once on the motherboard, you should see the options for Bios set up. Check your motherboard manual for more information.

it like your windows was corrupt
you need to reinstall your windows

Your hard drive may be corrupted. Try reinstalling the operating system, otherwise the motherboard is bad. Also, check the RAM.

You've probably reset the bios, so we won't belabor the point. Sounds like the motherboard is toast. You replaced the power supply, and that was probably the culprit, but it took out the MB as well.

A 478 board is older, but you should be able to eBay one with similar specs.
http://www.gigabyte.com.tw/Products/Motherboard/Products_Spec.aspx?ProductID=1863

To reset the bios to factory settings on most motherboards you need to short a jumper AFTER removing the battery.

It would be useful to know make and model of motherboard in question.

WARNING: DO NOT move CMOS jumper with battery iinstalled or power applied. Make sure you return the CMOS jumper to normal position before reinstalling the battery or powering up.

Sorry for the in your face warning but don't want you to damage the motherboard.

Regards B.

try boot from floppy disk if there is one floppy 

refix your ram after clean dust from it. aslo reset your bios settings,remove cmos cell for 15 minutes.then check.

Fiend your solution direct from Gigabyte. Here is your solution.....



http://www.gigabyte.com/motherboard/prob676ijt65/solution
884

1) Try re-seating the RAM
if it's still the same problem, then the power supply maybe bad.
Try with a good PS.

Usally blue screen errors are from ram. Do you have the right ram for that board?. Is the ram set to the right speed in bios?.