Myntekt :
I bought my PSU on the UK and the power plug is from the UK as well. So I bought an adaptor. Can I do this? Or should I just use my old PSU's power plug?
It's ok to use the adaptor, but it's better and cleaner to use the cable with the right plug.
The other way around (EU to UK) adaptors have a fuse built in, which may not be rated high enough for the intended purpose.