I have a case for an old PC which has kicked the bucket. After getting new innards, I'm now attempting to install a new PSU. However, rather annoyingly, the screw holes don't line up well. The PSU's holes are ~1mm above where they should be. There are two little ridges to hold up the PSU in the case, with a raised section on it. Should I file it off, or just get rid of the ridges?