Memory upgrade

[PDanes]

I have an old HP Compaq, still running Vista. I'd like to upgrade it to Win 10 - the specs claim it should be possible. In the process, I scavenged some memory modules from other old machines lying around, but have been unable to get any of them to work.

In particular, I have a Hynix 2GB module in the machine, which works fine. I tried adding other modules, all 2 GB, and not one of them worked, at all, even solo, yet they ALL worked in the machines from which I salvaged them, in various combinations.

The major difference I can see is on the chip's part number:

the working one is HYMP125U64CP8

the non-working ones are HYMP125U72CP8.

The working one has 64 in the part number, the non-working ones have 72.

The chips look slightly different physically as well - the 72 has an extra chip in the middle, while the 64 has an empty space there.

The motherboard is an IPIEL-LA, which is supposed to handle up to 8GB, and I have read threads from people one here that say they have made 8GB work with no problem, and are  running Win 10 on the board.

Any ideas on what is with these memory modules, and what can I use in this board?

[Paul_Tikkanen]

Hi:

When I look up the part number of your PC's working memory chip, it is a PC2-6400 memory module, correct?

I would try these.  I have used them in two of my HP business desktop PC's which are very picky about what memory they will run with.

https://www.newegg.com/g-skill-4gb-240-pin-ddr2-sdram/p/N82E16820231207?Item=N82E16820231207

[PDanes]

Both the working and non-working have:

2GB 2Rx8 PC2-6400-666-12

in the top row of text on the module. The second row has the numbers I gave  in the original post, and they differ only in the "64" vs "72" buried within the long number. The specs for both modules look the same:

http://www.hynix.com/datasheet/eng/module/details/module_08_HYMP125U64CP8.jsp

https://www.skhynix.com/eolproducts.view.do?srnm=HYMP125U72CP8&rk=08&rc=module

I don't understand what is different, or how I would be able to tell in advance whether or not a module will work in this board.

[PDanes]

The modules you linked to also look more like the working module. If you look at the images, the center of the module, just above the notch, has an empty space. My working module has that space as well. In all the non-working ones, there is a chip in that space, seemingly identical to other chips on the  module.

[Paul_Tikkanen · Accepted solution]

So, the way I'm looking at this, the non-working modules have 9 chips (5 on one side of the notch and 4 on the other) and the working one has 8 chips 4 & 4, correct?

It is my understanding that the extra chip is for ECC memory and the ones with 8 are non-ECC.

Your PC does not use ECC memory.

There is really no way to be 100% sure you get the right memory on the first go around--especially with older model PC's.

However, I am very sure the memory I posted will work in your PC.

[PDanes]

I see - I looked up ECC memory, and that seems to be the issue. I don't really understand why - it seems to me that the error-correcting function of such memory should be transparent to the board on which it lives. The whole point of error correction is to deliver data more reliably - why should the motherboard be concerned about the functionality of such modules? However, this is far from the only thing I don't understand about computer hardware - I'm mostly a database designer, and hardware is not nearly at the top of my skill stack.

I've gone through our entire pile of old computers, and found a bunch of modules with 9 chips, and a few with only 8. But they're all 1GB, so even if they work, I won't be able to pack the board as I'd like. However, I'll give it a try, and if it does work, at least I'll be ahead, and I can continue the hunt for some 2GB modules.

Back in a bit.

[Paul_Tikkanen]

I believe that ECC memory is only used on business class workstations and servers where precision is important.

Even my business-class desktop PC's don't support ECC memory.

Your consumer class PC does not have a memory controller on the motherboard that supports the ECC function, so that is why it doesn't work.

[PDanes]

Success! I first tried putting in three 1GB modules and leaving the old 2GB, but that didn't work. I remember vaguely that memory modules must be paired somehow, although I'm not sure of the exact definition of pairing. The computer I pirated these old modues from had three of them, two together and one alone, in the usual 2 + 2 configuration of memory slots on the board. Maybe it's they have to be the same IF they're paired, but they can work solo without a 'paired' partner?

In any case, I took out one of the 1GB modules, leaving the 2GB alone in one pair and two 1GB modules in the other pair, and it worked. Started right up, BIOS saw it and Vista booted normally, without so much as a passing comment, and now shows 4GB of RAM.

So thank you, that seems to be the answer. I will continue my hunt for 2GB non-ECC modules - this institution has lots of old computers, and I should be able to scare up something, or buy new ones if my scavenging fails, and I now know what to purchase.

If you ever make it to Prague, the beer is on me.

[Paul_Tikkanen]

You're very welcome.

I will never turn down a free beer.  😊