Deano wrote on 2023-11-11, 15:41:

Just got a AP440FX system without CPU, wondering it I should go for a Pentium Pro 200Mhz with 1MB Cache or not. The 1MB are more expensive and not sure if it has compatibility issues (motherboard manual only says up to the 512K version but probably was made before the 1MB came out).

Anybody tried that combo or seen any benchmarks between the 512KB and 1MB CPUs?

It should work without any issues.
I have a VS440FX and I changed the 256KB version with 1MB version without any additional measures and it is working normally.
Besides, there is even a clip on YT which shows your combination: https://www.youtube.com/watch?v=0Oxe5I1Urks

I was disappointed when I performed several benchmarks between the 256KB and 1MB and the differences were really negligible, no extra points for the 1MB version.
But then again in the server/workstation world the extra L2 cache could have been really useful.

I had issues with the PP 200 w/1Mb cache on a DFI 686IPA (weird lockups at boot) but it runs fine on my Intel VS440 also.

Deano wrote on 2023-11-11, 15:41:

Just got a AP440FX system without CPU, wondering it I should go for a Pentium Pro 200Mhz with 1MB Cache or not. The 1MB are more expensive and not sure if it has compatibility issues (motherboard manual only says up to the 512K version but probably was made before the 1MB came out).

Anybody tried that combo or seen any benchmarks between the 512KB and 1MB CPUs?

The 1MB Cache part seems to work without issue - https://www.youtube.com/watch?v=0Oxe5I1Urks

"I didn't set anything on the motherboard, I put in the cpu and it worked."

Nice ! one note about the 1Mb cache version: it does not have a good metal cap like the 256k/512k variants (no metal cap at all, just some type plastic/ceramic top) and runs very hot.

Deano wrote on 2023-11-11, 15:41:

Just got a AP440FX system without CPU, wondering it I should go for a Pentium Pro 200Mhz with 1MB Cache or not. The 1MB are more expensive and not sure if it has compatibility issues (motherboard manual only says up to the 512K version but probably was made before the 1MB came out).

Anybody tried that combo or seen any benchmarks between the 512KB and 1MB CPUs?

You are correct to question 1mb processors. they are not 100% compatible with all motherboards. I'd say it is 99.999% but I know of one motherboard the Asus P65UP5. The first hardware revision (1.2 if memory serves) will not post with 1mb chips. The much more common 1.41 revision is fully compatible. Over drive chips still ran perfectly with revision 1.2.

The GAMING differences between 256k, 512k, and 1024k are negligible. 256k to 1024k is only ~5-10% uplift in gaming and windows benchmarks. so yes. the 1024 is "better" but only if it costs no more than 10% of what you would pay for a 256k. That said, if you dont mind the extra cost for a bit of dick waving, I wont hold it against you.

we made a big benchmark sheet about it >>> Re: The Ultimate 686 Benchmark Comparison

Horun wrote on 2023-11-12, 17:48:

Nice ! one note about the 1Mb cache version: it does not have a good metal cap like the 256k/512k variants (no metal cap at all, just some type plastic/ceramic top) and runs very hot.

its actually an aluminum plate with a fiberglass base. ^.^

These chips (1mb) should not run hot. If your chip is hot, the heatsink isn't up to the task or you might have airflow issues.

That said, if you overclock, the heat will be factor VERY fast. going from 200 to 233 is common and should work fine on 90% of chips with no issues. over 250mhz the L2 cache will torpedo any further OC'ing attempts in the vast majority of cases.

Hmm ok, it feels like plastic. Wish it had the same good Gold plated cap of the 256k and 512k versions 😀 maybe the heatsinks for the 512k aren't good enough for 1Mb cache ones, that is what I am using and it gets very warm....not OC'd

luckybob wrote on 2023-11-15, 03:09:

The GAMING differences between 256k, 512k, and 1024k are negligible. 256k to 1024k is only ~5-10% uplift in gaming and windows benchmarks.

In my experience, the 256/512KB versions overclock much better, they’re usually fully stable @ 233 MHz, while none of my 1MB chips can do it. So, in this case, there’s really no performance difference at all.

Okay thanks everyone, I'll think i'll go for a 256/512KB at least to start with. At least its possible to get ones with coolers whereas all the 1MB i've seen don't come with coolers and buying the cooler on its own is harder than the CPU in this part of the world!

bloodem wrote on 2023-11-15, 05:33:

luckybob wrote on 2023-11-15, 03:09:

The GAMING differences between 256k, 512k, and 1024k are negligible. 256k to 1024k is only ~5-10% uplift in gaming and windows benchmarks.

In my experience, the 256/512KB versions overclock much better, they’re usually fully stable @ 233 MHz, while none of my 1MB chips can do it. So, in this case, there’s really no performance difference at all.

Never had any problems running 1MB version @ 233Mhz. Tested at least 10 CPUs over the years... But it does get hot!

With 1MB version running at 233Mhz I've sold the 333MHz overdrive as it's not that much faster.

kixs wrote on 2023-11-15, 08:46:

Never had any problems running 1MB version @ 233Mhz. Tested at least 10 CPUs over the years... But it does get hot!

With 1MB version running at 233Mhz I've sold the 333MHz overdrive as it's not that much faster.

Interesting! All three of my 1MB CPUs are unstable at 233 MHz, but they do work fine at stock speed.
I only tested them on one Socket 8 motherboard, though, so that might explain it. Maybe it's a matter of increased power consumption with the overclocked 1 MB CPU, and my motherboard just doesn't like it (it's definitely not a cooling issue, since I was using overkill coolers).

As a rule, I do not overclock my old hardware. I might do a run or two, just to scratch the itch, but its not the 90's anymore. If I want a faster computer, I have a AMD 5950X system to my right. if i'm trying to play a game thats too much for a ppro, i'll break out my Pentium 3. 😜

bloodem wrote on 2023-11-15, 09:07:

Interesting! All three of my 1MB CPUs are unstable at 233 MHz, but they do work fine at stock speed.
I only tested them on one Socket 8 motherboard, though, so that might explain it. Maybe it's a matter of increased power consumption with the overclocked 1 MB CPU, and my motherboard just doesn't like it (it's definitely not a cooling issue, since I was using overkill coolers).

With 3.30V VCore? Maybe you need 3,40-3,50V VCore for a stable 233 MHz.
The 1MB version has a TDP of ~47W. Extreme for a 1997 Socket CPU.
The L2 Cache was produced in 350nm, and the earlier Pentium Pro 256kb versions are produced with a 500nm L2 Cache. 512kb-1MB should have 350nm L2 Cache Dies.
The Core itself should have 350nmm, execpt the 150Mhz of the PPro, which should have 500nm.

I have a 256kb and 1MB PPro in my collection, but no Socket 8 mainboard for testing. Nice showcase CPUs, in special the Gold version.

luckybob wrote on 2023-11-15, 14:43:

As a rule, I do not overclock my old hardware. I might do a run or two, just to scratch the itch, but its not the 90's anymore. If I want a faster computer, I have a AMD 5950X system to my right. if i'm trying to play a game thats too much for a ppro, i'll break out my Pentium 3. 😜

I generally like "light overclocking", so I have strict rules (like never exceeding safe voltages, no matter how cheap/common the hardware is; in fact, I rarely increase the voltage at all).
I even have certain PCs that I specifically built with overclocking in mind, such as Slot A systems (goldfinger ftw!), or those with the legendary Celeron 300A. 😀

NostalgicAslinger wrote on 2023-11-15, 16:35:

With 3.30V VCore? Maybe you need 3,40-3,50V VCore for a stable 233 MHz.
The 1MB version has a TDP of ~47W. Extreme for a 1997 Socket CPU.

I only have one Socket 8 motherbard (the Intel VS440FX). As far as I know, I can't change the vcore on it (without modding), so I only tested with the default voltage.

A PPro @233, is that overclocked by multiplier or some off-standard FSB? i.e. is 3.5x supported and selectable on boards?

Multipliers weren't locked until the Pentium 2.

The Apollo MB has jumpers for 3.5v, a 4x multiplier and 66Mhz.
Do you feel lucky punk?! 😁

The manual also has this strange comment (unable to test as 256KB cache PPro for me),
"The 200 MHz Pentium Pro processor with 512 KB of cache memory is not supported on the AP440FX motherboard."

I did some testing few years ago. PPro 1M is on average 10% faster than 256k version. These tests were performed using 32-bit SW only.

And some power figures. When fully loades, the CPU alone consumes:

PPro 200/256 -> 36W
PPro 200/1M -> 48W
PPro 233/1M -> 55W

And few more, for context:

P233 MMX -> 22W
K6 233 -> 37W
PII 233 -> 39W

You can find more info here http://hw-museum.cz/article/5/cpu-history-tou … 1995---1999-/14

luckybob wrote on 2023-11-15, 22:39:

Multipliers weren't locked until the Pentium 2.

I'm aware of that, but didn't know whether or not PPro supported more than 3x which was the highest released ...