This poll was conducted to help users decide whether or not to alter their IIsi clock oscillator. I have attempted to gather as many case histories as possible to find some estimate of success and risk. The number of replies probably shows how rare this modification is but give the impression that success rates may be higher than the previous 80% estimate. 24 of 24 machines were able to run at 25 mhz when no add on boards were present. This is not a scientific survey but it is the best we have to work with.  Thanks to all who contributed to this poll.    Issues:  	Speed) 25 mhz to 27.5 mhz appears to be the norm for machines without 		add on cards. All reported machines were able to use 		25 mhz as long as no add on cards were present. Several Apple 		Nubus cards were in use. No machine with the Nubus adapter 		was able to go faster than 25 mhz. One wasn't even able to 		achieve 25 mhz with the Nubus adapter in place 	 		At speeds of 32 and 33 mhz, the startup sound is distorted and 		hi density floppy disk problems have been reported. 		 		Note: Unless specifically listed below, machines were not 			tested with a higher speed clock to failure. Hence, 			the 25 mhz operational machines may well work at 			higher speeds. 			 	Damage) One user reported pulling out the plating of one pad. This was 		repaired and the machine is operational. One other 		reported pulling the pin out of the original clock oscillator 		during desoldering. There is one second hand report of a user 		putting a gash in the motherboard with a slipped soldering iron. 		 		No reports of static discharge damage. 		 		No reports of high speed operation causing damage. 		 		Then again, I also don't have any reports from users of 		defective parachutes. 		 	Add on boards) Compatibility appears to be a problem with Apple Nubus 		Adapters. Several other add on boards have been used with 		success. See case histories 		 	Heat Sinks) Virtually all modified machines had a heat sink installed. 		These were often the TO-220 style power transistor type. Some 		used epoxy. Some used a dab of heat sink compound with a dab 		of cyanoacrylate glue. There was also use of a clamp with a 		bolt through the hole in the motherboard. 		 		 		 Case Histories:	  All speeds are the effective CPU speed (1/2 of clock oscillator). All reported CPU versions were 20 mhz.  1)  27.5 mhz operational. Ran for 10 minutes at 31 mhz before crashing.     No FPU or other add on card     Heatsinked CPU only     On 24 hours/day     No damage during installation     2)  27.5 mhz operational without Apple Nubus adapter. 25 mhz top speed with 	Apple Nubus card installed     Heatsinked CPU only     On 24 hours/day     No floppy problems     No damage during installation     3)  27.5 mhz operational. Unable to boot at 31 mhz     Heatsinked CPU only     No floppy problems     No damage during installation     4)  25 mhz operational     Works with the following two configurations 	 	  	a)	Realtech FPU adaptor card 			Realtech Cache card 			SuperMac 8*24 PDQsi 		 		b)  	SuperMac FPU adaptor card 			SuperMac Video Spigot 			SuperMac 8*24 PDQsi 			 5)	33 mhz operational 		Fuzzy startup sound 		Problems with hi density disks  6)	33 mhz operational 		Fuzzy startup sound 	Heat sink on CPU and chip to right of CPU 	 7)	25 mhz operational. Occasional crash at 33 mhz  8)	25 mhz operational. 	Using FPU rated at 16 mhz without difficulty 	 9)	25 mhz operational. 	PDS adapter with a Spectrum 24PDQsi graphics card and a  	VideoSpigot, a 20MHz FPU 	Heat sink on CPU 	 10)	25 mhz operational. 33 mhz failed after several hours.  11)	25 mhz operational 	 5/80+quicksilver/fpu(only upgrade) 	  12)	25 mhz operational. Tried 33 mhz - system won't start.   	Heat sink on CPU 	Configured with 		RealTech FPU/adapter card 		Supermac 8*24 PDQsi 		Realtech cache. 	CPU on continuously - no problems.  	Floppy works fine at 1.4MB @ 25 mhz 	 13) 25 mhz operational 	Heat sink on CPU 	 14) 25 mhz operational 	Heat sink on CPU 	 15) 25 mhz operational 	Heat sink on CPU 	 16) 25 mhz operational 	Heat sink on CPU 	 17) 25 mhz operational 	Heat sink on CPU 	On 17-19 hours per day 	 18) 25 mhz operational 	Heat sink on CPU + cooling fan 	No floppy problems at 25 mhz 	 19) 20 mhz operational. Bombed soon after startup at 25 mhz with Nubus Adapter 	20 mhz rated CPU 	RAM 70 ns in slots, 80 on motherboard 	 20) 25 mhz operational 	Heat sink added to CPU later. No damage while unheatsinked. 	Apple Nubus adapter with FPU installed. 	 21) 25 mhz operational 	Heat sink on CPU 	 22) 25 mhz operational 	Heat sink on CPU 	 23) 25 mhz operational 	Heat sink on CPU 	 24) 25 mhz operational 	Heat sink on CPU