World number 70 Poomjaeng continued to bleed errors after losing the opening session 7-1, and was duly punished with Welsh kid White finishing off the match in the same manner in which he had conducted himself throughout the match by contributing a fine century of 102.
Poomjaeng's highest break of the match was only 51 as he looked a shadow of the player who had accounted for former UK winner Stephen Maguire in the first round.
World number 41 White remains on course to become the first qualifier to reach the last four since Andy Hicks progressed to the semi-finals in 1995.
He will face Ricky Walden or Robert Milkins for a place in the last four, but he has Saturday morning off when he should have been facing Poomjaeng in their third session.
For the record, breaks of 71, 43, 83, 73 and 102 helped White over the line.
FIRST SESSION REPORT
Dechawat Poomjaeng endured a forgettable first session to trail Michael White 7-1 in the World Championship second round in Sheffield.
The world number 70 failed to replicate the form that accounted for Scotland's Stephen Maguire 10-9 in the first round, somehow managing to lose the fourth frame after missing the pack of reds three times using the spider.
There was some confusion among the crowd at the Crucible, but the rules state that a player loses the frame if he fails to hit an object ball when he can clearly see it.
It was a rare spectacle but in a performance of some poverty, it was probably apt that Poomjaeng should suffer the embarrassment of losing a frame with neither player potting a ball.
Apart from rolling in a break of 101 in the second frame, White only had to sit and wait for his chances - of which there were plenty - as much of the Thai player's performance mimicked the standard of a club player.
It would be interesting to hear what Maguire - the sixth seed and last year's semi-finalist - made of it all, with Poomjaeng's performance nowhere near the levels that had enthralled the crowd earlier in the week.
He again cut an animated figure in laughing and joking with the audience, but it all became a bit sad in the end. Especially when White holed the black to pinch the last frame of the evening for a 7-1 overnight lead.
There is every chance this match could end tomorrow with a session to spare with White needing only six more frames to reach the last eight.
For the record, White also made a 65 in the fifth frame with Poomjaeng's knock of 51 not enough to claim the eighth frame.
This is the first time either man has reached the last 16 of a ranking event, but Welshman White, only 21, handled the occasion better than his eccentric opponent.
Referee Michaela Tabb lost her concentration by plucking the white ball off the table for no reason in the final frame of the session, but it made little difference to the outcome of the evening.