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