Next attempt at a board that can hit 340 MHz --> It works!
So far, my P2 boards are just fine at 250 MHz. But, they all die above 320 MHz.
Frustratingly close to being able to run the @Wuerfel_21 emulators, but not quite there...
I'm not 100% sure it's thermal either, but maybe it is.
Anyway, gearing up for third version of this board and hoping that going from 2 to 4 layers will get me there. I'm pretty much keeping top and bottom the same and using one inner layer for 3.3V and one for 1.8 V. Also having a dedicated cap for every 3.3V and 1.8V pin, which may also help.
I do have some 5V signals on the 3.3V layer that I think I'll move to the 1.8V layer after looking at this.
Update: Seems to be able to run NeoYume and MegaYume game emulators, so maybe mission accomplished. Posting Eagle source and Gerbers here now.
Update2: Final version with LDO regulators on some pin groups posted here 11Nov23