Irinikus wrote on 2022-10-15, 17:50:

Do any of you know if this type of RAM will work in this machine? (It would allow me to load the machine up with 1.5GB of memory […]
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Do any of you know if this type of RAM will work in this machine? (It would allow me to load the machine up with 1.5GB of memory!)

They are 256MB EDO ECC server modules, and the Pentium Pro motherboard does support ECC.

Not compatible. Look at the contact fingers, they does not have vias that connects two fingers on front and back vs standard 72 pin simms. Will burn out if you try.

Cheers,

BitWrangler wrote on 2022-10-15, 18:07:

Someone perform the ritual of luckybob summoning, I'm sure he will have notes.

I've seen these modules. I've always assumed they are not compatible. 128mb is the maximum without going into the realm of proprietary.

pentiumspeed wrote on 2022-10-15, 23:26:

Irinikus wrote on 2022-10-15, 17:50:

Do any of you know if this type of RAM will work in this machine? (It would allow me to load the machine up with 1.5GB of memory […]
Show full quote

Do any of you know if this type of RAM will work in this machine? (It would allow me to load the machine up with 1.5GB of memory!)

They are 256MB EDO ECC server modules, and the Pentium Pro motherboard does support ECC.

Not compatible. Look at the contact fingers, they does not have vias that connects two fingers on front and back vs standard 72 pin simms. Will burn out if you try.

Cheers,

It was indeed the lack of the via at the top of each finger that made me question their compatibility and do more searching.

There are allot of sellers marketing them as SIMM’s, which is potentially dangerous!

768MB it will have to be then!

Thanks for all of your inputs, I really appreciate it!

Another question:

Is there a significant difference in performance between 60ns and 40ns EDO?

The problem with this is that I've only been able to find 64MB SIMM's @40ns, and this would limit the machine to 384MB, which would cause the machine to make excessive use of its page file, rendering the speed improvement null and void!

Measurable? Yes.

Practical? No.

luckybob wrote on 2022-10-16, 06:25:

Measurable? Yes.

Practical? No.

Thanks!

40ns: Be ware ram of that speed is usually 3.3v

This is probably the way I'm going to go:

https://www.ebay.com/itm/303649179445

These are the ones I use for 512mb on my tyan s1564d

Sphere478 wrote on 2022-10-16, 06:52:

https://www.ebay.com/itm/303649179445

These are the ones I use for 512mb on my tyan s1564d

Thanks for the suggestion, as that memory comes at a very good price. (The ECC memory is 3.3 times the price!)

Call me crazy though, as I do want to install ECC RAM, as it's one of few the tricks that the Pentium Pro (Socket-8) has up its sleeve! I know that it won't offer any performance benefit, but it is a rather cool feature, and one of the features which sets the Pentium Pro apart.

I'm crazy, I know!!!

Correction to last!

@Sphere478, I see that your dual Pentium Board also supports ECC memory, so it not purely a Pentium Pro thing!

Very nice board, by the way!!! 😀

Thinking about it, EDO offers better performance than FPM, so I'll definitely consider the RAM that you recommended!

Thx 😀 it treats me well. Wish it would overclock though.

Does "ECC" in the context of 72-pin SIMMs really mean anything other than parity (36 bit)? I.e. you can just use any old parity SIMMs for ECC mode, right?

ECC 72pin SIMMs are 10 ICs per side, providing 40 bits. HX chipset supports this as long as motherboard supports 40 bits ECC SIMMs.

36 bits SIMMs are parity always and will crashes the PC if parity error is caught. 32 bits is non-parity which you have now, and will not get caught if there's error which will corrupt the storage and issues, including windows breaking itself.

Best of all is ECC, which fixes bit errors on the run.

Cheers,

No, the chipset can use the one parity bit for error correction (ECC). And this one additional bit is also sufficient for this. The BIOS must have implemented a sufficient support for it. With the Intel Socket 7 chipsets only the 430HX could do it. On the Socket 8 / Slot1 chipsets, most of them could, except for the budget versions (440EX and 440ZX). With my ASUS P6NP5 (and T2P4) i can use ECC with 36Bit EDO modules.

Just realised OPs socket 8 is only 72 pin Simms, mine is 168 Pin EDO ECC Simms which I initially thought were SDR PC66 modules as the EDO ECC modules look identical except for the first notch being slightly closer to the outer edge.

Perhaps this is due to mine being a 440FX.

Wonder if my board support buffered EDO ECC ..only one way to find out I guess.

This board is based on the Intel 82440FX three chips PCI set and it has ECC support.

Irinikus wrote on 2022-10-16, 21:02:

This board is based on the Intel 82440FX three chips PCI set and it has ECC support. […]
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This board is based on the Intel 82440FX three chips PCI set and it has ECC support.

Mines a NEC job with integrated SCSI, Video and a few other server related things, seems 440FX came with a wide range of memory support.

You can see why I thought this was PC66 SDR

TrashPanda wrote on 2022-10-16, 20:52:

Just realised OPs socket 8 is only 72 pin Simms, mine is 168 Pin EDO ECC Simms which I initially thought were SDR PC66 modules as the EDO ECC modules look identical except for the first notch being slightly closer to the outer edge.

Perhaps this is due to mine being a 440FX.

Wonder if my board support buffered EDO ECC ..only one way to find out I guess.

I am pretty sure that electrically you can put 168 pin EDO slots on anything that has 64 bit bus paired Simms

with some trickery probably 30 pin simm motherboards if you wired the slot as stacked so it was only as wide as the bus?