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When did Intel start locking their CPU's ??

S

SPAnDAU

Senior member
I thought that Intel started locking their CPU's with the P2 266, but today I was working on a system with a P2 333 that was not locked. I didn't check the spec code, so I'm not sure if it is an engineering sample, but that's not very likely.

Were some of the 333's unlocked???
 
the 400 maybe? around the time of the celeron, but i could be wrong. look in the anandtech archives to find out.
 
they started around when the P2 350's were released. There were a few unlocked 350's, so they must have begun locking CPU's during the middle of production for the 350s
 
Actually, locking started back with the P120's (I've still got one) only FSB could be changed.
when the P2's came out at 66mhz bus, most were not locked.

Then the 350 @ 100 mhz bus came out, and most have been locked since then.
 
All CPU's made by Intel after August 1998 are locked.

Which coincidentally happens to be right around the advent of the P2 350.

Viper GTS
 
All 0.25micron cpus are locked, I bought the last one that wasnt locked, PII300mhz 0.35micron. And it shows, can just overclock it to 333mhz 😛
 
some pentium 133s were locked. They could do 2x and 3x but not 2.5 x multiplier. Also the pentium 166mmx was locked after people found out most could do 233 fine
 
I bought a PII 350 in Nov. '98 that was made in Aug. and not clock locked, it's on it's third owner still happily chugging along @ 450 (4.5 X 100).
 
My Celery 266 was locked I'm pretty sure (at least I never tried changing the multiplier). And of course the Celery 300a was locked 😉 I'm still using a few of those!
 
Intel CPUs were supposed to have been clock locked as to use one multiplier only as of August 1998.

All Celerons are clock locked. CPUs before 1998, starting with some of the PPGA Pentium MMXs were clock limited. Ceramic Pin Grid Array Pentium MMX were not locked or limited in any way.

All Pentium IIs which are not clock locked are supposed to be clock limited, in that the maximum multiplier they can use is the one they default to.

For example a Pentium II 300 has a default mutliplier of 4.5. It is able to use any multiplier up to 4.5, but when you set the multiplier to 5 or above, it will internally change the multiplier to 2, and you will boot up at 133MHz.

Intel made a limited run of Pentium 120 and Pentium 133 with a limited mutliplier as well, ie they won't recognise multipliers over 2.
 
Intel's first multiplier locked x86 cpu was the 8086. It was locked at 1.0x

Regarding the first x86 cpu locked at a multiplier other than 1.0x, that would be the 486DX2-50, which was locked 2.0x.

Intel briefly starting allowing multipliers to be user configurable with their P5 series. The late P5 chips and early P6 chips more or less allowed for the full range of user configurable multipliers. Starting with (I think) the PII-266, some multiplier options were disabled (specifically with some PII-266 chips, multipliers above 4.0x were not selectable).

Beyond that, I have no idea and defer to other posts in this thread. 🙂

-JC
 
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