after perusing many monitor cleaning threads for what seemed like many years I started to wash boards with the dollar store variety of Simple Green called Mean Green. the first board I ever washed was the power supply board for my Defender, cause I bought it separate and it was covered in probably 30 years worth of shit and there was no way I was going to rebuild it like that.
besides the fact that I didn't dry it 101% (it would make these awful sizzles under the caps when I tried to desolder) the operation turned out to be a success and I wound up doing it for a lot of games, even broken ones, afterward.
I don't have this luxury anymore because I quit my job, but while I was there I would spray the boards with the Simple/Mean Green first and then place them in the big kitchen sink in the back and use the intense water sprayer on hot water for the initial cleaning. I adopted the use of a toothbrush later on if there was any ruthless stuff caked on.. and then turned the water down to cold for the big rinse. rinsing is particularly important cause I don't know what'll happen if you leave the chemicals still on there and run it..
my approach to drying involved bathroom hand dryers early on, possibly about 20 cycles per whatever I was working on at the time.. until I found an extra hairdryer of my wife's sitting in the van, I kept it as a tool.
lots of people insist on using air compressors around sockets, like channelmanic mentioned, but I never did. with some finesse with the hairdryer blasting the socket at various angles you will eventually get the water to pop out. I focus on the sockets extensively just because you don't really know how much water is underneath.
the next part either involves you jumping in and operating on the board (power supply rebuilds, cap kits, etc.) or you could alternatively let the board sit overnight. I don't do anything fancy with fans or leaving boards upside down, I just let it sit in a spot where it won't fall off.
if you wash monitor chassis always make sure you remove the flybacks or any other crucial parts that don't have replacements first like width coils or other funky parts that I don't know the names of. I always remove transformers too.
now what I have observed happens with this Simple/Mean Green stuff is sometimes after you clean a board, it will develop this weird white film on it that you can't get off. for the times this has happened to me, I used a toothbrush sprayed with Windex and just cleaned any of the affected areas with it. you can re-wash with the Simple/Mean Green again if you would like. a rinse might be just enough too.. Windex won't hurt anything, it evaporates pretty well, but it might leave marks where you cleaned with it, so re-cleaning is optional.