"Self Built" Do you have a quality and adequate power supply? I have seen an incandescent lamp flicker when it was running on the same AC circuit during periods of heavy GPU usage.
I have a Corsair RM 650W.
Just tried exporting with software graphics only and it worked - guess it is probably something wrong with the GPU then? But as stated I have already had a GPU RMA'd so am wondering what is going on. Unless it might be how another component is interacting with the GPU?
Appears that it didn't work...the file finished exporting but is ridden with problems (blocky, artifact-ridden video at certain points)
I'm also having problems with audio being pure white noise when exporting clips intermittently. On the same part of a sequence for testing, one minute the audio is white noise after exporting (any codec/setting), the next it it is fine. Adobe support has "no idea" what the cause is.