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First post, by feipoa

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Has anyone tried 128 MB SIMMs in an Intel VS440FX motherboard? What about 3.3 V SIMMs? The manually specifically calls for up to 64 MB SIMMs, but was wondering if 128 MB would work. Also, the manual does not specifically mention 3.3 V SIMMs, so I assume it is 5 V only? Seems some Pentium Pro boards could take 5 V or 3.3 V SIMMs.

Board manual is here: http://www.elhvb.com/mobokive/Archive/Intel/V … FX_28181203.pdf

Last edited by feipoa on 2019-07-26, 23:41. Edited 1 time in total.

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Reply 2 of 8, by havli

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I have no idea about the voltage, but 128 MB SIMMs actually might work at full capacity. i440FX supports up to 1 GB of RAM and it really works (I have 4x 256 MB EDO DIMM in 440FX board). So 2x 128 or 4x 128 should be easy.

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Reply 3 of 8, by The Serpent Rider

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I don't think any "common" 440FX board knows how to deal with 3.3 SIMMs and manuals don't mention it either. In many cases SIMM slots are placed near AT/ATX connector with very obvious direct 5v feed from PSU. Does regular EDO DIMM even work at 3.3v?
Also I doubt that 440FX can work with buffered 128mb/256mb SIMMs or any sticks from HP servers. I tried some 128mb HP sticks, but they didn't boot.

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Reply 5 of 8, by kixs

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alvaro84 wrote:

Do 3.3V SIMMs have different keying?

No. It's the same.

I've used 128MB 3.3V memory in Amiga Blizzard 1230IV card that supposedly only supports 5V. It's works just fine so far... 🤣

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Reply 8 of 8, by RayeR

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kixs wrote on 2019-07-27, 06:41:

No. It's the same.

Interesting, I have found a JEDEC spec doc. where is drawing of 5V and 3V3 72p SIMMs and specially mentioned about a different keying! But there are also SIMM that use 3v3 memory chips and also includes LDO and maybe some level shifters that are mechanically compatible with 5V SIMMs.

I'm just wondering coz someone tells me he use 128MB 3v3 SIMM in his PPro board and it supply 3v3 correctly but my PPro board use std 5V SIMMs... So trying to figure out how it works. I doubt the board have some smart voltage detection.

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