Win 7 boot up freezes

Hi, I am new to the forum. I have been upgrading a pc I purchased a few months back....not sure why cos I don't use it. Anyway the pc has an AMD A4 processor, gigabyte FM2+ mobo, and 4GB of DDR 3 ram and a 256GB SSD. It has nothing on it as it was a clean machine I bought....I booted it up and all was ok. Over the last few weeks I: upgraded to 12GB ram so added an 8GB to the 4...OK no problems.
Added a TP Link USB wifi adaptor...again no problems. Then added wireless keyboard & mouse...no problem. Finally I changed from an A4 to an A10 processor and it installed ok with lots of green ticks on the screen but also 2 messages relating to graphics which said restart is required. When I restarted the pc it hung after the windows logo. Tried system repair, restore etc but no joy still hanging on boot. Removed the A10 and replaced the A4 and all seems ok again. Is there a trick to upgrading the processor?

Welcome to the Forum.

You wrote that the SSD "has nothing on it as it was a clean machine I bought". Did you do a Win 7 Clean install or it came with Win 7 OS? I wouldn't trust a win 7 installed on second hand computer.
- Did you upgraded the MB BIOS to the last version?
- Can you boot on Safe Boot (f8)?

Hi, thanks for looking....I bought the machine pre-loaded with win 7 from a local computer shop with a 3 month warranty....however, I only switched it on when I bought it to see it running, and promptly allowed the warranty to expire. It was running ok (I think) until I added the A10 processor (also bought 2nd hand). I didn't upgrade the bios and I cannot boot in safe mode with the A10 fitted.

It can be that your A10 CPU isn't good or isn't appropriate to your MB.
Witch Gigabyte MB you have?
Update your BIOS.

mobo is GA-F2A88XM-DS2....I will update the bios.

For what I've seen, GA-F2A88XM-DS2 is compatible with A10 Kaveri AMD APU.
It may be only a BIOS update.