computer technician? you smart?

Alright, I have got a little problem. Asking for some help from anyone on here with some computer repair experience. I build computers often. I do not have any real test equipment, which might come in handy for problems like the one I have.

Okay I have a mainboard motherboard with an 800 megahertz processer that both seem to work. I switched the processor to another computer and it ran fine. I have a radeon video card, and all other hardware needed. Meaning i have the essentials, ram hard-drive cd-rom floppy, and nothing else connected. Ram is compatible with my system as is the processor. But there is a problem.
Upon power-up motherboard light goes on, hard drive engages and begins to spin cd-rom works. But nothing appears on the monitor. The monitor is operational, I checked. Also I switched the video card with another, which did nothing. I also switched to a videocard that was a PCI and still nothing. So there it is, anyone got any ideas?

I figure either the motherboard is bad or the processor. Will the hard drive spin if the motherboard is not operational. My guess is a long as there is power it will spin. Also it is a jumperless motherboard.
So if anyone has ran into this problem before, then let me know. Also is there somewhere that i can get the equipment to test the motherboard. Equipment that will test the slots and other thing. Well thanks for your help!
-----blayde-----
keep it coming.....

You might want to put this in a different forum, the Tutorial forum is generally for sharing information rather than questions...

Now, I am hardly a computer repair-guy, so I'll speak of what I learned in a class I took rather than my non-existent-extensive experience., but do you have a POST-card? Or maybe inbuilt on the motherboard? It will be a 2 digit little LED display, and if there is a problem during the Power-On-Self-Test sequence, you can read off the POST code (hexidecimal error number) to see how far it got before stuff went awry. But no, I don't know the error codes by heart, they might vary depending on your motherboard or BIOS manufacturer.

Connect the pc speaker and give us the post code beeps. If you hear nothing then it probally is the M/B or CPU
Then you just do the olo componet swapping procedure.

What type of processor is it? Is it an Athlon, Duron, Pentium III, Celeron? If it is an Athlon chip your power supply has to have a GTA rating of at least 42 to turn the chip over upon startup. that could be one problem. One test we run at the shop is to uplug EVERYTHING, I mean everything, IDE cables from drives everything. The only thing you leave plugged in the is processor, video card, and ram, don't even plug in the keyboard and mouse, just the monitor cable and see if it posts. If it doesn't then it's the video card, ram, processor, or motherboard. After that it is just a trial and error process to see which component it is. Now if it posts then it means that you might have a bad IDE cable or a bad hard drive, CD-ROM, or floppy. IDE cables rarely go bad but it has happened as well as floppy drives, and HDs, and CD-ROMs. But if all else fails try replacing the power supply to a 250 or 300w with at least a 60 GTA rating. Hope it works out for you. PM if you get it to work.