VOGONS


First post, by squareguy

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I am currently working on finding a CPU for my next build that will be my primary retro system. Right now I am working with a Pentium II 400 that is unlocked, has the good cache controller and 5ns cache chips. I have other CPU's I need to look at but have not gotten around to opening them up yet.

My motherboard is an AOpen AX6BC (2.59 latest BIOS) that does not support changing voltage or going down to a 66-MHz bus with a 100-MHz bus CPU. Neither of these is an issue as I am going to mod the bus to 66-MHz and voltage to 2.1V on the CPU itself. Then I can select 66-MHz or 100-MHz in BIOS when setting speed. I have successfully made both of these mods to another CPU, so no worries there.

I have a hot air SMD rework setup and I am going to remove the 2 5ns cache chips and replace with 4.4ns or faster cache chips from a donor P2/P3 CPU. I will do this with an undesirable CPU first for testing.

My question:

Has anyone else done this, any tips or tricks you would like to share?

My goal is to have a Pentium II that can go from 133-MHz up to 450-500-MHz for this build.

Gateway 2000 Case and 200-Watt PSU
Intel SE440BX-2 Motherboard
Intel Pentium III 450 CPU
Micron 384MB SDRAM (3x128)
Compaq Voodoo3 3500 TV Graphics Card
Turtle Beach Santa Cruz Sound Card
Western Digital 7200-RPM, 8MB-Cache, 160GB Hard Drive
Windows 98 SE

Reply 1 of 19, by stamasd

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Even if you find an unlocked PII (which were only made until about the first half of 1998 IIRC, they aren't exactly unlocked, but rather limited in multiplier ranges... with the default multiplier being the highest they can use. So an "unlocked" PII-400 will go up to 4x maximum AFAIK.

I/O, I/O,
It's off to disk I go,
With a bit and a byte
And a read and a write,
I/O, I/O

Reply 2 of 19, by Deksor

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Well that's not an issue here : if 533MHz is too much for it, he'd just need to the multiplier to 3.5x and it will be allright.

All I can say is that concerning multipliers, I've seen an old thread on the internet where people talked about germans that managed to unlock pentium 2s ... But nobody knew how. Maybe that's just an old hoax from the late 90's, maybe not, but too little informations (if any existed) made it through the 20 last years ...

Trying to identify old hardware ? Visit Ultimate Retro - Project's thread The Ultimate Retro project - a stason.org/TH99 alternative

Reply 3 of 19, by squareguy

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Already have the 400 and pretty sure I posted at 500 with it. Getting a few 333's soon.

Gateway 2000 Case and 200-Watt PSU
Intel SE440BX-2 Motherboard
Intel Pentium III 450 CPU
Micron 384MB SDRAM (3x128)
Compaq Voodoo3 3500 TV Graphics Card
Turtle Beach Santa Cruz Sound Card
Western Digital 7200-RPM, 8MB-Cache, 160GB Hard Drive
Windows 98 SE

Reply 4 of 19, by Tetrium

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stamasd wrote:

Even if you find an unlocked PII (which were only made until about the first half of 1998 IIRC, they aren't exactly unlocked, but rather limited in multiplier ranges... with the default multiplier being the highest they can use. So an "unlocked" PII-400 will go up to 4x maximum AFAIK.

They could actually use higher multipliers.

Taken from this thread

Tetrium wrote:
Heres the pics I promised earlier The first 2 are from an unlocked P2-400 […]
Show full quote

Heres the pics I promised earlier
The first 2 are from an unlocked P2-400

DSC00272.jpg

DSC00276.jpg

Strangely it wouldn't post at 400Mhz with a FSB of 66, 366Mhz was the highest it would go.
The folowing 2 also were unlocked. Perhaps it might help others more easilly chase down unlocked Deschutes of their own 😉

DSC00278.jpg

DSC00279.jpg

The 2 others I tested (a 350Mhz and a 300Mhz one) were fully locked and had manufacturing locations of PHILIPPINES and COSTA RICA

All three of the unlocked ones also went down to 133Mhz btw

Enjoy!

More info can be found here

My guess is that some had higher multipliers unlocked so these could be used in both 100MHz FSB (needing lower CPU multipliers) and 66MHz FSB (needing higher multipliers).
I don't know for sure though.

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My retro rigs (old topic)
Interesting Vogons threads (links to Vogonswiki)
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Reply 5 of 19, by squareguy

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Yeah unlocked is easy to find if you know what to look for.

DSC00279_LI.jpg
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So looking at his CPU the 9829 tells us:

9 = made in Malaysia
8 = made in 1998
29 = made in week 29

I buy week 30 or younger but i think it goes a week or so past that.

Gateway 2000 Case and 200-Watt PSU
Intel SE440BX-2 Motherboard
Intel Pentium III 450 CPU
Micron 384MB SDRAM (3x128)
Compaq Voodoo3 3500 TV Graphics Card
Turtle Beach Santa Cruz Sound Card
Western Digital 7200-RPM, 8MB-Cache, 160GB Hard Drive
Windows 98 SE

Reply 6 of 19, by squareguy

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As far as the multiplier limiting it seems I read that a lot of the overclocking boards would report to the CPU that the bus was 66 when it was really 100. This seemed to give more available multipliers in the multiplier limited CPU's. IE, tricking them for more speed.

Gateway 2000 Case and 200-Watt PSU
Intel SE440BX-2 Motherboard
Intel Pentium III 450 CPU
Micron 384MB SDRAM (3x128)
Compaq Voodoo3 3500 TV Graphics Card
Turtle Beach Santa Cruz Sound Card
Western Digital 7200-RPM, 8MB-Cache, 160GB Hard Drive
Windows 98 SE

Reply 7 of 19, by squareguy

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So, has anyone been gutsy enough to replace cache chips? I guess I am the guinea pig then.

Looks like donor for cache is going to be a P3 500.

Gateway 2000 Case and 200-Watt PSU
Intel SE440BX-2 Motherboard
Intel Pentium III 450 CPU
Micron 384MB SDRAM (3x128)
Compaq Voodoo3 3500 TV Graphics Card
Turtle Beach Santa Cruz Sound Card
Western Digital 7200-RPM, 8MB-Cache, 160GB Hard Drive
Windows 98 SE

Reply 8 of 19, by Deksor

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squareguy wrote:

As far as the multiplier limiting it seems I read that a lot of the overclocking boards would report to the CPU that the bus was 66 when it was really 100. This seemed to give more available multipliers in the multiplier limited CPU's. IE, tricking them for more speed.

Yeah I've heared that on an article written at the time about the abit BH6, which offers that functionality. But I was never able to prove that yet (I don't have any unlocked pentium 2 except old Klamath 🙁 )

Trying to identify old hardware ? Visit Ultimate Retro - Project's thread The Ultimate Retro project - a stason.org/TH99 alternative

Reply 9 of 19, by squareguy

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Deksor

Here is a cheap one one to try out on that BH6 https://www.ebay.com/itm/302832395190

First system that I actually built myself was a BH6 and Celeron 300A

That combination was straight out of Anandtech, man I miss those days hehe

Gateway 2000 Case and 200-Watt PSU
Intel SE440BX-2 Motherboard
Intel Pentium III 450 CPU
Micron 384MB SDRAM (3x128)
Compaq Voodoo3 3500 TV Graphics Card
Turtle Beach Santa Cruz Sound Card
Western Digital 7200-RPM, 8MB-Cache, 160GB Hard Drive
Windows 98 SE

Reply 10 of 19, by squareguy

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If anyone is interested I can get pictures of resistor locations and what they do for voltage and bus speed.

Gateway 2000 Case and 200-Watt PSU
Intel SE440BX-2 Motherboard
Intel Pentium III 450 CPU
Micron 384MB SDRAM (3x128)
Compaq Voodoo3 3500 TV Graphics Card
Turtle Beach Santa Cruz Sound Card
Western Digital 7200-RPM, 8MB-Cache, 160GB Hard Drive
Windows 98 SE

Reply 11 of 19, by Thermalwrong

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That would be interesting - I've been wanting to try something like this for a few months now - I've got an Aopen MX6B-EZ which has multiplier settings, but sadly none of my deschutes CPUs have been pre week 30 so far.

I'm interested to know how it's set, since information about this has essentially fallen off of the internet. I was looking into it a few months ago and there was nothing conclusive from back in the day, but we might be able to find something new since opening up a Pentium II processor isn't so risky these days as it used to be. Specifically being able to control 66 / 100MHz from the processor side might be very useful for me.

PS: Me too! the first PC I was allowed to spec (thanks dad 😀 ) was an Abit BH6 with a 300A, that was promptly clocked up to 450MHz 😁

Reply 12 of 19, by Deksor

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Thanks for trying to help me finding a cheap "unlocked" pentium II, but the shipping really kills the deal to me as I'm not from the US, I'm in europe.

About Celeron 300A, well so far I couldn't OC any of them to 450MHz x)

I have two of them, both are OEM versions. One can boot windows at 450MHz and do quite a lot of stuff, but sometimes you'll get an app crashing, a lockup, etc. The other one can't even start windows, it will crash during the startup.
For sure I tried to overvolt them, but it didn't change anything ... I guess I was really unlucky x) (And maybe OEM celerons are worse clockers than retail ones ?)

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Reply 13 of 19, by Thermalwrong

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That's surprising - I seem to recall my 300A might have required 2.1v to be fully stable though, so maybe that could help?

There's someone in the UK selling 12 Pentium II CPUs, mostly 333Mhz and many with datecodes before August 1998, sadly they refuse to part the lot out, I don't want 12 of them, just ONE 😒

Reply 14 of 19, by Deksor

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I said I tried to overvolt it, but it didn't help (went up to 2.8v !!)

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Reply 15 of 19, by squareguy

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I never saw a 300A OEM, not saying they didn't exist, just never saw one. I think mine ran up to 504 but I cannot remember voltage, probably 2.1 or so.

Gateway 2000 Case and 200-Watt PSU
Intel SE440BX-2 Motherboard
Intel Pentium III 450 CPU
Micron 384MB SDRAM (3x128)
Compaq Voodoo3 3500 TV Graphics Card
Turtle Beach Santa Cruz Sound Card
Western Digital 7200-RPM, 8MB-Cache, 160GB Hard Drive
Windows 98 SE

Reply 16 of 19, by squareguy

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I have started modding the P2 400 I am probably going to use. I have a couple 333's I am going to look at soon.

Modded 100-MHz bus down to 66-MHz - Good. now I can select either 66-MHz or 100-MHz in BIOS

Modded VID to 2.1V - Good. confirmed with DVM on regulator

Removed 5.0ns CACHE - good. CPU works like normal but is now detected by software as a Celeron hehe

Have several options for new Cache 4.4ns, 4ns, and 3.6ns. Will not decide until after checking core at various speeds and looking at the 333's

Running a CPU burn in at 450-MHz right now. After I get the core lapped (not good contact with HSF) and some thermal compound (metal to metal right now) I will test at 500-MHz

CPU CACHE runs at half core speed

5.0ns = 200-MHz, this is what it came with

4.4ns = 225-MHz

4.0ns = 250-MHz

3.6ns = 275-MHz

Gateway 2000 Case and 200-Watt PSU
Intel SE440BX-2 Motherboard
Intel Pentium III 450 CPU
Micron 384MB SDRAM (3x128)
Compaq Voodoo3 3500 TV Graphics Card
Turtle Beach Santa Cruz Sound Card
Western Digital 7200-RPM, 8MB-Cache, 160GB Hard Drive
Windows 98 SE

Reply 17 of 19, by gerwin

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This is an interesting project, thanks for sharing your observations so far. I am especially curious about how the L2 cache transplant wil work out. Any progress in the past weeks?

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Reply 18 of 19, by Deksor

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Deksor wrote on 2018-10-12, 23:53:

Well that's not an issue here : if 533MHz is too much for it, he'd just need to the multiplier to 3.5x and it will be allright.

All I can say is that concerning multipliers, I've seen an old thread on the internet where people talked about germans that managed to unlock pentium 2s ... But nobody knew how. Maybe that's just an old hoax from the late 90's, maybe not, but too little informations (if any existed) made it through the 20 last years ...

Good news everyone !

I just found a lost goldmine https://web.archive.org/web/20010718083705/ht … ntel_multi.html and it might be the Germans the post I read years ago was referring to.

Many articles from the time that seem to explain how to unlock pentium 2s !

Trying to identify old hardware ? Visit Ultimate Retro - Project's thread The Ultimate Retro project - a stason.org/TH99 alternative

Reply 19 of 19, by gerwin

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Deksor wrote on 2021-11-25, 23:49:

I just found a lost goldmine https://web.archive.org/web/20010718083705/ht … ntel_multi.html and it might be the Germans the post I read years ago was referring to.
Many articles from the time that seem to explain how to unlock pentium 2s !

I browsed through those a bit. It is an okay read, but afterwards I cannot say I have learned anything useful that I did not already know. Neither does it inspire me to try something that I haven't already tried with those processors.
Some of the titles for the articles are misleading, suggesting a hack method is in that paragraph, but then the actual text is limited to explaining intel's design. Intel's design was never a mystery or discovery since that was explained in the intel datasheets to begin with.

In addition there is very limited benefit in getting more flexibility out of the pentium II. Getting an early enough semi-unlocked one already allows for a range of 100/133 to around 400MHz. Now if it was about the Pentium III instead it would be a different matter.

--> ISA Soundcard Overview // Doom MBF 2.04 // SetMul