Upgraded my motherboard and CPU but now my monitor isn't showing an image

My guess is you have run into the most common problem with big upgrades.

When you first Install Windows on your machine, what gets installed on your HDD is customized to match what the process finds as available hardware. That includes all the Devices in your system, and MANY of those are actually components of the mobo. Each of those devices has the required device driver installed on your HDD and noted in the Windows Registry, but the drivers for all those thousands of devices you do NOT have in your system are left out.

Now you have upgraded by replacing both the mobo and the CPU. So VERY likely drivers for the new system are missing, and Windows cannot boot without them. The total solution is to re-Install Windows from scratch, but DO NOT do that! That is a huge process and risks losing stuff. You MAY be able to solve this with a much simpler and safer process.

Get your original Windows Install CD, or at least an Install CD or the SAME version of Windows. Put it into your optical drive. Boot directly into BIOS Setup and go to where you configure the Boot Sequence. Set it to boot from the Install CD in the optical drive first, and then from your HDD second (assuming you want it to boot from your old HDD when this is done). SAVE and Exit, and the machine will boot from the Install CD and ask you what to do. Do NOT do a normal Install! Instead, look in the menu choices for a Repair Install and do that. This process will assess what hardware devices are in your system NOW, and what device drivers are already installed, and what drivers are missing. Then it will fix all those driver mis-matches. When the process is finished, back out and shut down, and remove the CD from the drive. Then boot up again.

If this works completely, your system will boot cleanly. Immediately go into Control Panel ... System ... Device Manager. Look carefully though all the devices listed for any that have a yellow triangle flag on them. Those indicate devices that the system still does not have a good driver for, and that needs to be fixed. If you're really lucky, you won't have any of those. Or, maybe you'll have a few that you need to find and install drivers for.

If this does NOT work, your system won't boot cleanly. You might try to force it to boot in SAFE MODE. That does not attempt to load all the device drivers, and thus does not enable everything. But often you can boot this way and use the system enough to identify the missing drivers and install them.

I'm afraid that OS has nothing to do with problems like that if you can't get enough of the picture to get into BIOS.

Try resettling you CPU.

CountMike has a good point, and I missed the detail that nothing shows on the monitor at all. Just to be sure of that detail, there is a difference between two situations. One is that the monitor never shows anything except, perhaps, its own error message saying it's getting no signal. The other is that the monitor does show some computer start-up screens, then blanks out when it tries to boot into Windows. So, which is it, OP?

An additional thought to consider for you. You replaced the mobo. In doing this, did you check VERY carefully that screw holes in your new mobo match up exactly with ALL of the case standoffs already in place for your old mobo? It is essential that there should be NO standoff under the new mobo that does NOT match a mounting hole in the mobo. Otherwise that misplaced standoff can cause a short on the mobo bottom side.