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Which Pentium IIs can be underclocked?

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Reply 120 of 217, by ux-3

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Tetrium wrote:

Could you type the full markings of your 400 MALAY?
I will do as requested and test my semi-unlocks in a couple other boards...when it's not roasting HOT in my attic!!

I did already:

ux-3 wrote:

80523PY400512 SL2S7
98300966-0436 MALAY

gerwin wrote:

I think it is just how intel makes their CPU's, and don't think mainboards can do much about it. I looked before but most info on the net on P-II multiplier locks is flawed. What is on vogons is the best info yet. The only thing that I still cannot really grasp is the principle behind that intel newspeed.exe utility.

Gervin, I consider it most likely to be dealing with identical CPUs. However, on my Mobo, I get a limitited multi of 4x, whereas he gets 5.5x.

Reply 121 of 217, by gerwin

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sliderider wrote:

I'm wondering if maybe a Coppermine Celeron with 66mhz FSB can be underclocked enough if put on a slocket adapter to be able to run DOS games slowly enough to be playable. ???

All retail P-2/3 celerons are completely factory multiplier locked, and the 66MHz FSB is already on the lowest value. So zero options there.
There were some engineering samples celeron 333 and such for sale a while ago, I was curious about them but they did not ship to europe...

gerwin wrote:

GerWin, I consider it most likely to be dealing with identical CPUs. However, on my Mobo, I get a limitited multi of 4x, whereas he gets 5.5x.

The conclusion I made a year ago is that the maximum semi-unlocked P-II multiplier depends on the FSB used, at 66MHz FSB you can use higher multipliers than at 100MHz.

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Reply 122 of 217, by Tetrium

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sliderider wrote:

I'm wondering if maybe a Coppermine Celeron with 66mhz FSB can be underclocked enough if put on a slocket adapter to be able to run DOS games slowly enough to be playable. ???

A slotket won't make any difference other then being able to equip a slot 1 board with an always fully locked celeron.
The lowest FSB I found on a couple (mainly older) slot 1 and PPGA s370 boards is 50mhz.

ux-3 wrote:

I did already:

ux-3 wrote:

80523PY400512 SL2S7
98300966-0436 MALAY

Sorry, I did look through a couple of pages but couldn't find it.

ux-3 wrote:
gerwin wrote:

I think it is just how intel makes their CPU's, and don't think mainboards can do much about it. I looked before but most info on the net on P-II multiplier locks is flawed. What is on vogons is the best info yet. The only thing that I still cannot really grasp is the principle behind that intel newspeed.exe utility.

Gervin, I consider it most likely to be dealing with identical CPUs. However, on my Mobo, I get a limitited multi of 4x, whereas he gets 5.5x.

It still won't hurt to try a couple motherboards I have here. When I'm done I'll post my findings in this thread.
Still theres a chance it's the cpu and not the board.

Reply 123 of 217, by ux-3

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As far as I can tell, I am not able to use multis over 4x, even on 66MHz.

But according to ancient wisdom, it makes a difference if the board is simply set to run at 66MHz by choice of the user, or if the pin is physically at 0V, which would make the board default to 66MHz anyway. According to ancient wisdom, there are boards which even have seperate settings in their bios for those two distinct choices.

Reply 124 of 217, by Tetrium

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ux-3 wrote:

As far as I can tell, I am not able to use multis over 4x, even on 66MHz.

WAIT a minute...are you saying you CAN change the multiplier of your P2 400?

Reply 125 of 217, by ux-3

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Tetrium wrote:
ux-3 wrote:

As far as I can tell, I am not able to use multis over 4x, even on 66MHz.

WAIT a minute...are you saying you CAN change the multiplier of your P2 400?

I am not sure if I understand you correctly. I can run the p2-400 with any of these:
2x, 2.5x, 3x, 3.5x, 4x. This leads to actual speeds between 133 MHz (2x66MHz) and 400MHz (4x100MHz). Of course, the FSB could be increased to 112MHz, for 448 MHz.

Fom the pics you posted, you have even more choices. So I am not sure we talk about the same thing.

Perhaps we should diffentiate between multi (cpu speed/fsb speed) and default multi. I can change the multi, not the default multi.

Reply 126 of 217, by Tetrium

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ux-3 wrote:
I am not sure if I understand you correctly. I can run the p2-400 with any of these: 2x, 2.5x, 3x, 3.5x, 4x. This leads to actua […]
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Tetrium wrote:
ux-3 wrote:

As far as I can tell, I am not able to use multis over 4x, even on 66MHz.

WAIT a minute...are you saying you CAN change the multiplier of your P2 400?

I am not sure if I understand you correctly. I can run the p2-400 with any of these:
2x, 2.5x, 3x, 3.5x, 4x. This leads to actual speeds between 133 MHz (2x66MHz) and 400MHz (4x100MHz). Of course, the FSB could be increased to 112MHz, for 448 MHz.

Fom the pics you posted, you have even more choices. So I am not sure we talk about the same thing.

Perhaps we should diffentiate between multi (cpu speed/fsb speed) and default multi. I can change the multi, not the default multi.

Ok, now I understand. I was thinking yours was fully locked.
In theory cpu's have an array of available multi's. Intel later started disabling some or most multi's until they decided to lock all other multi's.

I got a couple P1mmx 200 that have a 3.5x multi and a couple that don't. They only go up to 3x.
Hence the name 'multiplier limited'

Both our P2's are multiplier limited but yours has more of the multipliers disabled then mine. I got no idea as to why this is though.

Reply 127 of 217, by ux-3

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Another posting went to hell cause of timeout. So read yourself about Sel66/100:

http://www.anandtech.com/show/105

http://www.cpu-central.com/Hardware.asp?id=3& … =cpus&display=1

Retro PC warning: The things you own end up owning you.

Reply 128 of 217, by Great Hierophant

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ux-3 wrote:

Another posting went to hell cause of timeout. So read yourself about Sel66/100:

http://www.anandtech.com/show/105

http://www.cpu-central.com/Hardware.asp?id=3& … =cpus&display=1

Those old articles focused more on overclocking than underclocking, but they imply that it is possible to set any multiplier by setting the 100/66 pin to 66. Apparently, as 66x5.0=330, Intel didn't seem to care as that clock speed is lower than 350/400MHz. One of them also states that the PII 450 is completely locked regardless of setting.

It is quite likely that later versions of the 350/400 would not work with this trick either. Obviously, the safe approach would be to avoid later steppings of these processors.

http://nerdlypleasures.blogspot.com/ - Nerdly Pleasures - My Retro Gaming, Computing & Tech Blog

Reply 130 of 217, by ux-3

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Great Hierophant wrote:

Those old articles focused more on overclocking than underclocking, but they imply that it is possible to set any multiplier by setting the 100/66 pin to 66. Apparently, as 66x5.0=330, Intel didn't seem to care as that clock speed is lower than 350/400MHz.

To me, atm there seems to be only one possible expaination to deal with tetriums vs. my CPU other than actual physical cpu difference.

A mainboard could completely ignore the pin information the cpu provides. If you set it to fsb66, it will override to 66 no matter what the relevant pin voltage is. I suppose the p3b-f does it this way.

A mainboard or mod could alternatively set the pin voltage to physically act as fsb66 system. The bx chip will then see a fsb66 cpu and act accordingly.

From my links, it does make a difference to the cpu lock if fsb66 is caused by override or physically. And that difference is exploited by the Abit BH6 as it offers both methods for a good reason. You can physically set fsb66 to unlock the cpu and then override to 100. The CPU will unlock cause its sensors claim fsb66 but it will actually run at 100.

Reply 131 of 217, by ux-3

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Update:

My muliplier limited P2-400 can run with 4.5x and 5x as well. I just haven't figured out a reproducible path to unlock it. Every once in a while, the cpu breaks the multi-lock. From then on, it allows multis 4.5x and 5.0x as well and will accept the change of multi to anything between 2x and 5x repeatably. As soon as I power down or use a hard reset, the cpu falls back into the locked state. A reset with STRG-ALT-DEL will leave the cpu in the unlocked state.

This observation was made on an AOPEN MX 6B EZ. So it may very well be possible, that a different mobo will unlock this thing every time.

Aside:

Tetrium wrote:

I got a couple P1mmx 200 that have a 3.5x multi and a couple that don't. They only go up to 3x.
Hence the name 'multiplier limited'

How do those without the 3.5x respond when you set 3.5x? Do they run at 100 MHz?

Reply 132 of 217, by Tetrium

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ux-3 wrote:

Aside:

Tetrium wrote:

I got a couple P1mmx 200 that have a 3.5x multi and a couple that don't. They only go up to 3x.
Hence the name 'multiplier limited'

How do those without the 3.5x respond when you set 3.5x? Do they run at 100 MHz?

They will have 1 locked and one unlocked multiplier pin, as if one of the multi's is soldered shut on the motherboard itself.
They will only have 2.5x and 3x iirc. Some may actually be completely locked. I once tested all my P1 mmx 200's but don't know where I left that sheet of paper. If I find it again, I'll post the results here.

Reply 133 of 217, by TheLazy1

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I wonder...
If the clock generator on a board can do 66-133 in theory shouldn't it also be capable of a 33MHz FSB or lower?

I know it's kinda insane but I think a P2 at 66MHz would be pretty cool.

Reply 134 of 217, by TheLazy1

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Aww, my PII won't start up.
The power LED just blinks, I'll try cleaning the connector but I fear my only unlocked chip is toast.

🙁

Reply 136 of 217, by Tetrium

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Yes, you'll need to provide us with more info. It could be anything that's causing the problem, bad motherboard, bad ram, bad PSU. Have you tried swapping hardware? Tried resetting the bios?

Reply 138 of 217, by Tetrium

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TheLazy1 wrote:

Sorry, was just venting a bit 😀
It is definitely the processor, swapping with another makes it boot fine.

It's a shame really.

So what happened to your cpu? Did you zap it?

Reply 139 of 217, by TheLazy1

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I grabbed it from a machine on it's way to the dump, I guess a cooked CPU could have been the reason why. 😁
I probably have another somewhere though, kinda annoying that the later ones were also locked downwards.