Thanks for the offers JG and Peter. I'm more than happy to release a couple of beer tokens for anything that gets my feeble machine up to 512mb but don't want anyone to be out of pocket. I only bought the ram off ebay because no one else bid (no one else is daft enough to be using a pc that old I guess) so I got it for the minimum 99p plus the same again in postage. I can't imagine that ten year old ram types are in great demand but who knows. They want £25 a stick in the shops but I doubt if they sell any.
I'm still a bit puzzled why it actually works at all but only at half its nominal size. I downloaded the pdf file for the motherboard off the Intel site (D815EEA) and it says it can take either ECC or non ECC ram but it will will only run ECC in non ECC mode. In other pcs when I've tried ECC ram it doesn't work at all. Then there's the single sided, double sided ram issue but it says it should be able to cope with two sticks of double sided so I'm still puzzled. The ram that's in it now is all single sided - one stick of
128mb and two of 64mb. The ram I bought was double sided. Maybe it's a buffering issue and it really wants unbuffered ram like the manual says but I'm buggered if I actually know what that's all about.
The Crucial scan tool says I want 2 of these.
formatting link
Note that they have only 8 chips on each side rather than 9. The ones I bought have 9. Dividing by 3 seems to be a parity issue so clearly I want something that isn't divisible by 3. If you have anything that seems to fit the bill let me know.