Having to wait 5 x 20 minutes is only possible if you are leaving games quite often.
As the FAQ says, the timer starts at 5 x 5 minutes :
You will be placed in the low priority queue for 5 games. If you continuously leave,** the low priority queue timers increase from 5 minutes per game to 10 minutes per game and then capping out at 20 minutes per game.**
If you only left one game there is absolutely no punishment, you need to leave several games to trigger the low priority queue ( the 5 x 5 minutes part ) it doesn't happen just because "my pc died" once, you need to wait 20 minutes between games only if you've left quite a few games recently.