The BX chipset can't handle high density SDRAM chips, so 512MB sticks or single sided 256MB sticks (8/9 chips) can't be used. 768MB is maximum for the SE440BX-2. Make sure to clean the contacts of your stick before putting them in.

Don't use vague terms like "high density". What was "high density" in 1999 was "low density" by 2000, instead give the relevant chip densities. i440BX's mem controller can handle max 128Mb chips. 512MB double-sided DIMMs and 256MB singled-sided ones use 256Mb chips - and note the capitalization, it's factor 8 relevant.

Also note that "single-sided" doesn't refer to whether there are chips physically on both sides.

Another kind of RAM the i440BX doesn't like is 16-chip single-sided DIMMs with 16Mx4 or 32Mx4 chips (often sold as "Via only"), even though the chips are only 64Mb or 128Mb

mkubiak402, could you be a bit more specific on what happens whith the DIMMs that don't "work"? Based on your symptoms we can tell you what's going on.

- With 256Mb chips, you'd expect half the capacity (i.e. the first 128Mb per chip) to show.
- With 16-chip single-sided DIMMs, you'd expect the computer not to boot at all and beep a memory error at you.
- With compatible but defective DIMMs, worst-case the computer wouldn't boot and beep memory errors, otherwise it would appear to work but Memtest would show errors after anywhere between a few seconds and a few hours.

And yes, 1GB on a BX requires 4 DIMM slots, so no-go on the SE440BX-2.

if "single-sided" doesn't refer to whether there are chips physically on both sides what is it?

and if i want to fill it with 3 256mg sticks what do i need to look for? 32M x 64?

mkubiak402 wrote:

if "single-sided" doesn't refer to whether there are chips physically on both sides what is it?

The number of banks, i.e. data lines. A single-sided DIMM contains 1 bank, i.e. 64 data lines. A double-sided DIMM contains 2 banks, i.e. 128 data lines.

Most (S)DRAM chips used on DIMMs have 8 data lines, eg. 16Mx8, so a densitiy of 16Megabits per line times 8 lines. That gives you a chip capacity of 128Mbits.

Now, if you stick eight of those on a DIMM, you have 128MB total capacity and 64 data lines, so you've got a 1 bank, single sided DIMM. Generally you'd expect to see 8 chips on one side and nothing on the other, but DIMMs with four on each side also exist, and they are still single-sided.

Conversely, you have 128Mb chips with 8Mx16 organization. Same capacity, but twice the data lines. Four of those make a single bank, eight give you a double bank, even if they're all on the same side.

and if i want to fill it with 3 256mg sticks what do i need to look for? 32M x 64?

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You need double-sided DIMMs with 16Mx8 128Mb chips. As for notation like "32Mx64", that's for the whole DIMM and on the whole unhelpful, as you don't know whether it's referring to 8 chips with 32Mx8 (256Mb), or 16 chips with 32Mx4 (128Mb). In this case, neither will work correctly, as the 256Mb chips are too big, and will only be detected as 128Mb, so the DIMM will only be detected as 128MB. 32Mx4 chips are worse, they won't run at all.

>90% of 16-chip 256MB DIMMs will work correctly as they have 16Mx8 chips on them, only DIMMs with 32Mx4 will not, so look for 16 chips and if in doubt, look up the specs of the chips themselves on the DIMM. As I said earlier, good manufacturer-branded DIMMs are generally a safe bet, as unbuffered DIMMs with 32Mx4 chips are outside of JEDEC standards and the chip manufacturers stick to those religiously.

dionb wrote:

You need double-sided DIMMs with 16Mx8 128Mb chips. As for notation like "32Mx64", that's for the whole DIMM and on the whole unhelpful, as you don't know whether it's referring to 8 chips with 32Mx8 (256Mb), or 16 chips with 32Mx4 (128Mb). In this case, neither will work correctly, as the 256Mb chips are too big, and will only be detected as 128Mb, so the DIMM will only be detected as 128MB. 32Mx4 chips are worse, they won't run at all.

>90% of 16-chip 256MB DIMMs will work correctly as they have 16Mx8 chips on them, only DIMMs with 32Mx4 will not, so look for 16 chips and if in doubt, look up the specs of the chips themselves on the DIMM. As I said earlier, good manufacturer-branded DIMMs are generally a safe bet, as unbuffered DIMMs with 32Mx4 chips are outside of JEDEC standards and the chip manufacturers stick to those religiously.

I got my hands on SE440BX-2 a couple of years ago and did some checking/testing.
From somewhere I found out and noted "256Mb DIMMs should use 128Mbit components not 64Mbit (bus loading issues)"

Also after googling around to find out where that I got that information from, I found this: Intel SE440BX-2 not stable with 3 DIMMs https://arstechnica.com/civis/viewtopic.php?f=8&t=452220

I didn't do any further exploration - this was all back in 2017 and the motherboard is now in a cardboard box with 3x128M DIMMs installed, tested and working.
My investigation was limited to discovering that none of the spare 256Mb sticks I had worked, and that the board+CPU wasn't scrap.