i need help pretty bad

[manoby1]

I just built a new tower using old parts from another computer, when i first booted it up it worked fine but i had green pixels so i switched montiors and it worked fine again. After shutting down and turning it back on the computer blue screened, and restart. After that i went throigh trouble shooting and system restored to an earlier date, which allowed it not to blue screen, but was stuck on the 'starting windows' screen for 10 minutes until i restarted, this time it worked. But unfortunately, it was running so slow skype couldn't even run. I'm pretty afraid i messed something up bad and i dont have much experience with computers, only basic enough knowledge to put them together. Help would be greatly appreciated, i am also currently on my phone.

 

[Wolfshadw]

New build from old parts. Once put together did you reinstall Windows? If not, that would be your first step.

-Wolf sends

 

[SkyMembrane]

I just built a new tower using old parts from another computer, when i first booted it up it worked fine but i had green pixels so i switched montiors and it worked fine again. After shutting down and turning it back on the computer blue screened, and restart. After that i went throigh trouble shooting and system restored to an earlier date, which allowed it not to blue screen, but was stuck on the 'starting windows' screen for 10 minutes until i restarted, this time it worked. But unfortunately, it was running so slow skype couldn't even run. I'm pretty afraid i messed something up bad and i dont have much experience with computers, only basic enough knowledge to put them together. Help would be greatly appreciated, i am also currently on my phone.

As wolf said, even if the HDD you salvaged already had Windows, installing it again would be your best bet. I would also like to know, did you take the pieces from only one computer or from multiple old computers? Your PSU (Power Supply Unit) might not be powerful enough for the new system and that would mean your parts are running underpowered when the entire system asks for it's share of power. Finally, make sure that all your drivers are up to date and running properly, since the ones from the old system might not be fully compatible with the one your built.