Probably just a density issue. If Max RAM is 1GB and there are 4 DIMM slots you need low density 256MB 100Mhz SDRAM DIMMs to max it out (I forget if they need to be double sided).

dont have to, but its a safe bet that double sided 256MB SDRAM will be compatible

Unknown_K wrote on 2024-04-04, 08:11:

[...]
low density

"Low" or "high" density is a totally relative term and what is high density one day is low density the next. Please specify which density you mean by "low density" in this case.

i440BX will always be able to handle 64Mb chips (eg. 8Mx8) and usually can do 128Mb (eg 16Mx8) as well (the latter will be a BIOS limit). So a SIMM with 16 8Mx8 chips will reliably give you 128MB. In most cases 8 16Mx8 will give you 128MB too, and 16 16Mx8 will give you 256MB. 256Mb chips (32Mx8) will work at half capacity at best on a BX board.

Aside from density there can also be limits in the wiring. Some boards only accept two or three double-sided DIMMs, if more are installed the last two may only be single-sided. In that case higher density is actually the answer - if your 128MB DIMM with 16 8Mx8 chips is being detected as 64MB in DIMM3 or 4, replace it with a 128MB DIMM with 8 16Mx8 chips for the full 128MB.

Looking at this specific board, the manual uses pretty confused terminology, but given the following two statements:

maximum memory size is 1GB SDRAM [...] Those modules can be populated in any order […]
Show full quote

maximum memory size is 1GB
SDRAM
[...]
Those modules can be populated in any order

It's implied that 128Mb density is supported, and that all four DIMMs are fully wired.

So it appears that the DIMMs that are working at half capacity will have 256Mb chips.

OP, could you post the model numbers of the chips on your DIMMs?

dionb wrote on 2024-04-04, 09:25:

"Low" or "high" density is a totally relative term and what is high density one day is low density the next. Please specify whic […]
Show full quote

Unknown_K wrote on 2024-04-04, 08:11:

[...]
low density

"Low" or "high" density is a totally relative term and what is high density one day is low density the next. Please specify which density you mean by "low density" in this case.

i440BX will always be able to handle 64Mb chips (eg. 8Mx8) and usually can do 128Mb (eg 16Mx8) as well (the latter will be a BIOS limit). So a SIMM with 16 8Mx8 chips will reliably give you 128MB. In most cases 8 16Mx8 will give you 128MB too, and 16 16Mx8 will give you 256MB. 256Mb chips (32Mx8) will work at half capacity at best on a BX board.

Aside from density there can also be limits in the wiring. Some boards only accept two or three double-sided DIMMs, if more are installed the last two may only be single-sided. In that case higher density is actually the answer - if your 128MB DIMM with 16 8Mx8 chips is being detected as 64MB in DIMM3 or 4, replace it with a 128MB DIMM with 8 16Mx8 chips for the full 128MB.

Looking at this specific board, the manual uses pretty confused terminology, but given the following two statements:

maximum memory size is 1GB SDRAM [...] Those modules can be populated in any order […]
Show full quote

maximum memory size is 1GB
SDRAM
[...]
Those modules can be populated in any order

It's implied that 128Mb density is supported, and that all four DIMMs are fully wired.

So it appears that the DIMMs that are working at half capacity will have 256Mb chips.

OP, could you post the model numbers of the chips on your DIMMs?

In general Low density = 8 ICs on one side, High density = 16 ICs 8 on each side. BX will only handle low density single sided sticks and anything above 768Mb is pretty damn sketchy and not all BX chipsets will allow it, the BX6 2.0 even though it has 4 ram slots still only wants 768Mb in single sided low density sticks.

Trashbytes wrote on 2024-04-04, 09:31:

[...]

In general Low density = 8 ICs on one side, High density = 16 ICs 8 on each side.

No, that's single sided vs double sided. Density is a property of the chips, not of the number of the sticks.

BX will only handle low density single sided sticks and anything above 768Mb is pretty damn sketchy and not all BX chipsets will allow it, the BX6 2.0 even though it has 4 ram slots still only wants 768Mb in single sided low density sticks.

Again, specify what you mean by "low density", i.e. give a number.

You cannot go over 512MB with single-sided DIMMs on a BX board as the max per single sided DIMM is 128MB (assuming 128Mb density). To reach 768MB on a BX board you need at least two double-sided 256MB DIMMs with 16 128Mb chips.

Seems you have had this little argument before so no need to rehash it, You can hit 768Mb with three 256Mb sticks even on a BX board as you suggest.

Looking that up its dual rank 16x8 256 MB sticks, 128MB per side 16 chips total. <--This is for BX steping 2, version 1 didn't support 16x8 and only supported 8x8 config, OP doesn't need to worry about version 1 with a BX6 2.0

Switched to using rank to try to clarify things better.

I used to own this mainboard! I had it with a Celeron 300A overclocked to 450 MHz! Those were the days!
Advice : Stick to single sided memory sticks, and your mainboard will probably read the right capacity.
I think 4x 128 for a total of 512 MB is realistic for this board. I used to run it with 2 x 128.

hilram wrote on 2024-04-04, 12:44:

I used to own this mainboard! I had it with a Celeron 300A overclocked to 450 MHz! Those were the days!
Advice : Stick to single sided memory sticks, and your mainboard will probably read the right capacity.
I think 4x 128 for a total of 512 MB is realistic for this board. I used to run it with 2 x 128.

Its the perfect amount for 98 too