That era's RAM capacity is auto detected by SPD so there's no jumpers for that. Are you sure your two 64mb sticks are actually 64mb? Can you take a detailed picture of the ram sticks so we can read the markings on the chips?

I can't read any motherboard markings from your picture so no idea if there's actually a limitation but it does look like an intel based chipset. For a socket 7 intel based board, the limits would typically be much higher than that iirc. I think the cheapest 430vx goes to 128mb total with 64mb cache-able.

As an aside, that's something you'll have to check into. With many (not all) Pentium MMX systems, they typically only 'cache' up to about 64mb and in DOS/Win9x, it's used in a 'top down' fashion. So installing more than that on those kinds of systems will actually decrease performance considerably.

It's an issue with "low density" vs. "high density" memory--something to do with number of RAS lines, etc., too complicated for me to completely understand or explain.

I personally would forget it and just get two 32MB, 60ns EDO SIMMs and be done with it, since the DIMMs you have won't work and you need something else anyway. As pointed out above, only 64MB is cacheable so you don't want to go over that. If you want 128MB or 256MB you might build a Super Socket 7 or Slot 1 or Socket 370 machine instead.

here are the RAM sticks , I was only going to use 1 to get to 64MB due to what was said above :

I have also 2 x 32MB DSS SDRAM PC-100 168 Pins ticks coming so maybe those will work ? I read somewhere the VX chipset has some funny limitations of single vs double sided for SD RAM

32MB EDO chips are expensive and hard to find so want to stick with SD RAM

funnily enough found a 32MB DS in my box of goodies and it works .. so thats the answer ... only double sided SDRAM 32MB seems to work ...

I have very similar Samsung one-sided module running on 430TX based Socket 7 motherboard.
The sticker reads "PC133U-333-542 M366S0823ETS-C75"
The chips marking is almost identical, with the last letter begin E instead of D (you have K4S640832D chips, I have K4S640832E), but their specs looks the same.
I have no issues whatsoever using CAS latency of 2 clocks (the chipset is using 66MHz anyway), entire capacity is seen.

32MB sticks will probably be recognized in whole.
PS: If you want to help people identifying the motherboard put some more effort on the photos.

Omarkoman wrote on 2023-04-19, 04:27:

here are the RAM sticks , I was only going to use 1 to get to 64MB due to what was said above : […]
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here are the RAM sticks , I was only going to use 1 to get to 64MB due to what was said above :

I have also 2 x 32MB DSS SDRAM PC-100 168 Pins ticks coming so maybe those will work ? I read somewhere the VX chipset has some funny limitations of single vs double sided for SD RAM

No, double vs single sided limitations are due to motherboard design. VX can't handle higher density chips, but has no trouble with double-sided DIMMs.

But... that northbridge in your pic isn't i430VX. I can't make out what it is, but it's a BGA chip and only i430HX and i430TX have BGA northbridges. i430VX has a QFP package. Given i430HX doesn't support SDRAM this must be i430TX - if it's even an Intel chipset (although it looks like one).

i430TX can handle up to 128Mb (16MB) chips for DIMMs up to 256MB, so these 64MB DIMMs with 64Mb chips shouldn't be a problem. So something doesn't fit...

However it's really hard to make out anything definite given the pics. If you want us to help ID the board and figure out what's going on, we need better pics, preferably of the whole board outside of the system.

32MB EDO chips are expensive and hard to find so want to stick with SD RAM

32MB EDO chips :?

32MB (or indeed Mb) EDO chips are very unusual, you'd normally expect 16Mb or 64Mb, and I've never seen EDO chips over 64Mb (64Mb = 8MB, 32MB would be 256Mb...).

Are you talking about EDO modules (SIMMs) rather than chips?

Yes sorry edo simm modules not chips. Im trying to get to 64mb so i thought little technicalities how i spell or write out MB or Mb wont be a punishment so much.

I will disconnect the cables and take better pics. Apologies. Just have bad experience from past with old parts pulling things apart after being together for 30 years doesnt always work putting back and things get damaged.

Even with the very limited pics, that board screams "PC Chips". If so, it's probably the M550, though I can't confirm with these pics.

And I assume you're trying to get to 64MB, not 64mb. When talking about memory issues, you really need to be accurate with bits and Bytes (not to mention Mega vs milli...)

dionb wrote on 2023-04-19, 08:37:

Even with the very limited pics, that board screams "PC Chips". If so, it's probably the M550, though I can't confirm with these pics.

Looks indeed identical, even the version v5.6 in the corner of the board 😀
https://theretroweb.com/motherboard/image/m55 … ff052891076.jpg

Yep thats the board, thats what i meant guys, lot of experience and keen eye here.

On another note, any common places where can i get a pci bracket with ps2 connector and cable for the motherboard header? And same for usb? Would love to use an optical ps2 vs current ball serial mouse.

Omarkoman wrote on 2023-04-19, 08:58:

On another note, any common places where can i get a pci bracket with ps2 connector and cable for the motherboard header? And same for usb? Would love to use an optical ps2 vs current ball serial mouse.

Problem is pinouts for those things aren't standardized- PS/2 never was and USB wasn't yet.

Fortunately both are documented in the manual:
https://theretroweb.com/motherboard/manual/m5 … 54603118269.pdf

USB is 8p vs newer 9p, but the layout of those 8p corresponds to the 9-pin, so you can just go for any modern USB bracket.

PS/2 is pretty odd (particularly the presence of pin 5) even for the time. You're probably best off getting any PS/2 bracket you can find and manually hooking the pins to the correct wires.

I generally just get brackets like that on eBay, unless I happen to find one locally.

Btw, according to that manual, the board should accept up to 64MB DIMMs - and again, the i430TX can accept up to 256MB DIMMs normally with up to 128Mb chip density. Have you tried single DIMMs in both DIMM slots separately?

Btw, this board and mine too has jumpers to configure DIMM voltage between 3.3v and 5v.
Does it affect SIMMs too? Like, is it required to have DIMM voltage to be set to 5v when SIMM modules are used (sure, never together with DIMM)?

The datasheet for 430TX say it drives 3.3v outputs and its inputs are 5v tolerant, so I'd guess it's only about the DIMM vcc, and it's not related to memory interface (IO bank vccio) at all, but I'd like to know for sure.

vstrakh wrote on 2023-04-19, 09:33:

Btw, this board and mine too has jumpers to configure DIMM voltage between 3.3v and 5v.
Does it affect SIMMs too? Like, is it required to have DIMM voltage to be set to 5v when SIMM modules are used (sure, never together with DIMM)?

The datasheet for 430TX say it drives 3.3v outputs and its inputs are 5v tolerant, so I'd guess it's only about the DIMM vcc, and it's not related to memory interface (IO bank vccio) at all, but I'd like to know for sure.

The manual says:

Mit dem Jumpern JP1, JP2 wird die Betriebsspannung des zu verwendenden DIMM-Speichers
ausgewählt.

(Emphasis mine) - this explicitly refers to DIMM voltage, not SIMM.

A lot of PC Chips boards have this jumper and I've never really understood it - 168p DIMMs are keyed for voltage - the second key is different for 3.3V and 5V, so it should be physically impossible to insert 3.3V and 5V DIMMs into the same slot. These slots are keyed for 3.3V, so the only setting that makes sense is 2-3 for both JP1 and JP2.

Note that SIMM and DIMM can be combined if both use the same technology. Both FP and EDO DIMMs exist - even if much rarer than SDRAM - and 3.3V EDO DIMMs can be combined with 5V EDO SIMMs if the board is wired to allow it - which this one should be. The manual explicitly allows for this (see page 14), with the following caveat:

Bei Bestückung von DIMM-Sockel 2 dürfen zusätzlich nur die SIMM-Sockel 3 und 4 bestückt
werden; die Sockel 1 und 2 müssen dann frei bleiben.

So if you used DIMM slot 2, you may not use SIMM slots 1 and 2, only 3 and 4.