VOGONS


First post, by Sphere478

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I’ve been doing some mad experiments with my dual processor motherboard.

While encountering the multiplier locks on some of my chips this gave me an idea,

Maybe I could get one running at 166 and the other running at 200?🤷‍♂️ Why? Because for science!

I started out by setting 3x multi

I installed a pentium mmx 166 and 200. With the 200 in the primary socket.

It posts and detects 2 processors at 200mhz
Cpu-z even says dual 200mhz

But…
Super pi 16k says: 5.031 cpu0 vs 5.813 cpu1

Reboot and install actual pentium 200s and we get: 5.046 cpu0 vs 5.110 cpu1

What does it all mean? 🤔 I’ll let you decide.

Test conditions:
-Tyan s1564D (converted from S) w/jan j2 bios
-win2ksp4
-super pi mod 1.5
-affinity set between cpu 0 and 1 for different tests.
-Priority: real time.
-Asymmetric test cpu0 sy060 cpu1 sl27k
-symmetric test s-spec matched (will post numbers later)

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Reply 1 of 8, by dionb

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What does it all mean? 🤔 I’ll let you decide.

Unless you found some way of altering the multiplier settings per CPU, you overclocked a Pentium 166MMX to 200MHz. Nothing more or less.

If you want asymmetrical multi-processing, you need to go for a chipset that facilitates it. Take a look at the SparcStation 20 for an extreme and yet easy example. You can run 3 CPUs at two different speeds on those things without the OS (Solaris) even batting an eyelid.

Reply 2 of 8, by Sphere478

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dionb wrote on 2022-01-09, 15:56:

What does it all mean? 🤔 I’ll let you decide.

Unless you found some way of altering the multiplier settings per CPU, you overclocked a Pentium 166MMX to 200MHz. Nothing more or less.

If you want asymmetrical multi-processing, you need to go for a chipset that facilitates it. Take a look at the SparcStation 20 for an extreme and yet easy example. You can run 3 CPUs at two different speeds on those things without the OS (Solaris) even batting an eyelid.

I think the second cpu may have been still running at 166mhz

Even though it said 200 in cpuz the results in super pi suggest a larger difference than if they were both running at 200.

The 166 mmx won’t go over 2.5x multiplier through the bf0,1,2 pins so if it is going at 200 then how did that happen, and if it isn’t that explains the lower super pi score

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Reply 4 of 8, by Anonymous Coward

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Ha, that's interesting.
I could kind of understand why intel wouldn't want people to know about this, since they would lose money with buyers opting for a slower second CPU. But if that were the case, you'd think they try to disable this feature completely.

So what's the deal with matching s-specs and batches? I always remember that being really important for SMP setups...but apparently mismatched CPUs work together just fine?

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Reply 6 of 8, by Sphere478

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Anonymous Coward wrote on 2022-01-10, 01:22:

Ha, that's interesting.
I could kind of understand why intel wouldn't want people to know about this, since they would lose money with buyers opting for a slower second CPU. But if that were the case, you'd think they try to disable this feature completely.

So what's the deal with matching s-specs and batches? I always remember that being really important for SMP setups...but apparently mismatched CPUs work together just fine?

🤷‍♂️

Maybe so you get consistent performance between cores?

I suppose one reason would be to avoid a p54 and a p55 being in the same machine

Also cpus of different voltages.

But as we all know about any p55c can take 2.8v even if they list 2.2 on the package, just like at 166 I bet a 233 could take 2.2v

I was thinking about trying to do a p54c and a p55c earlier but decided I liked my motherboard.

I bet at 2.8v both chips would probably work at 133 but that’s getting pretty sketch and didn’t want to break anything.

SUCCESSFUL K6-2+ to K6-3+ Full Cache Enable Mod
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Tyan S1564S to S1564D single to dual processor conversion (also s1563 and s1562)
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Socket 5/7/SS7 (Motherboard) Tweaker
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The coolest socket 7 motherboard that you’ve never heard of

Reply 7 of 8, by Tiido

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Symmetric vs asymmetric doesn't mean same CPUs but what the CPUs have access to. Asymmetric multiprocessing machine can have one CPU be able to access things that other(s) cannot while symmetric systems have all the CPUs having equal access to all of the resources.

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Reply 8 of 8, by Sphere478

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Tiido wrote on 2022-01-10, 04:28:

Symmetric vs asymmetric doesn't mean same CPUs but what the CPUs have access to. Asymmetric multiprocessing machine can have one CPU be able to access things that other(s) cannot while symmetric systems have all the CPUs having equal access to all of the resources.

Asymmetrically clocked? 🤔

SUCCESSFUL K6-2+ to K6-3+ Full Cache Enable Mod
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Tyan S1564S to S1564D single to dual processor conversion (also s1563 and s1562)
-
Socket 5/7/SS7 (Motherboard) Tweaker
-
The coolest socket 7 motherboard that you’ve never heard of