<!-- from fixya rte -->Gateway desktop screen is black - Gateway Computers & Internet

So you replaced the motherboard.
Well the systems are like laptops so you need to check LCD cable inverter and the LCD screen.
eres one that had a motherboard problem but the screen seems ok.GATEWAY ZX4300 01E ALL IN ONE AS IS FOR PARTS <<< i buy part as is when it system don't power up because its not screen related.

or pay seperate

Gateway All in One ZX4300 41 Inverter Board

Gateway All in One ZX4300 41 Inverter Board Cable DD0EL2IV000

Gateway All in One ZX4300 LCD Video Cable DDEL2CLC000

check if the system is compatible.

Will it boot? Fan spin? LED's blink? Sound? Try connecting to a external monitor, does it show desktop? The screen is all black, no cursor at top left? No "ghost Image" in the screen when viewed in a bright light? I would look at the inverter board, backlighting, ribbon cable in the rear of the monitor, the LCD screen, your laptop has some miles on it. Not sure about a fuse on a laptop motherboard, don't see that often. Take a look at this may help you troubleshoot: http://www.youtube.com/watch?v=2Yi6GNFcP3w
ALSO Gateway Support may help: https://support.gateway.com/s/Mobile/Gateway/7305GZ/4694nv.shtml

Re set the screen resolution to a resolution that your screen can handle.

try to press the auto on your monitor. so that it will adjust automatically on the screen.

That indicates a hardware problem. From your description I would check the cpu or suspect it as being the problem. It can be a ram problem as well.

Did you make any changes recently (add memory, etc.)? Does it make any beeping noises on startup? I've had this problem occur when putting in the wrong type of memory. If you haven't added memory and there is beeping on startup, find the manufacturer of the MOBO and you should be able to find a beep startup code to tell you what the issue is.

BLACK SCREEN WHEN START . STAY BLACK

I had a computer that done that once, turned out to be memory. Mine wasn't a Gateway though but might be the same problem. Just something I have seen, maybe that will help.

Does backlight stay on, or does it look like the screen is turned off? If it looks like it is turned off, can you look extremely closely and see your desktop if held in good light?