266MHz my *rse. OK, the 030 doesn't generate that much heat but 50->133MHz with cryogenic cooling may be possible. As long as he temerature gradient is steep enough, you can siphon the heat away.
However, the memory on the card is driven at the same FSB as the CPU. Since you aren't cooling those and tbey aren't likely to be the 3.3v kind that were used in the last PC's to actually use SIMMs I strongly doubt your claim that the system boots.
People have tried to clock 66MHz 68060 cards with liquid cooling to 80MHz, the heat generated is not that great (probably less at 50MHz than the full 68030 is). However, the physical limitation on these overclocking has almost always been down to memory speed. None of the existing amiga accelerators have been designed to support such high FSB. Even the PPC cards use a 50/60/66MHz FSB and they took some effort to design.
No "I supercooled my cpu and ran it at stupid-MHz overclock" is going to change the fact that the other subsystems of the card cannot cope.
If you wanted to get a 680x0 >100MHz, you'd want a latest mask 68060 + SDRAM memory and a suitable memory controller designed for 100MHz+ FSB operation, as is found on the CT60 card for atari falcon for instance.
Nothing on the amiga motherboard is remotely affected by an accelerators local clockspeed, so your claims that the mouse is too fast etc. are completely untenable.
But do keep it up, it's entertaining :-D
