PC memory

[bbcmicro]

I am looking for some PC memory for my 915pm/915gm/915gvm/910glm series MSI motherboard (Manual doesn't say which is the model I bought, seller described it as 915gm...) Hopefully, this will be all that is required to get my system back up and running that has been in repair for 7 months (Takes me a while to save up for stuff!) Crucial's wizard isn't working for me (No drop down menus) and I don't have a specific model anyway.
This is what I got from the manual:

Supports two 64-bit wide DDR data channels
Availiable bandwith up to 3.2GB/s (DDR 400) for single channel mode and 6.4 GB/s (DDR 400) for dual-channel mode
Supports 128mb, 256mb,or 512mb DDR technologies
Supports only x8, x16 DDR devices with 2-bank

Later in the manual

Install at least one DIMM module in the slots. You can install either double- or single-sided modules to suit your own needs.

In the motherboard itself the slots are marked with 2.5v

I hope this is enough. I am looking for a combination of 1 or 2 modules, with total memory or 1-2GB, but not exceeding, and it must fit the system described above. Could I be any more specific :(
The above about mempry, and the whole memory system makes no sense to me whatsoever. I just hoped that the motherboard I got would support all my existing memory. Guess I was unlucky! It didn't physically fit. It was the right length, but the middle notch was a little out. Could someone please tell me a sensible price to pay, a link to where I can get some or offer me some themselves?

To trade I have the memory from my system that doesn't fit the new motherboard, two sticks of 512mb, both marked with the following sticker:

512MB 1Rx8 PC2-400U-444-12-DO
512MB, DDR2, 533, C14

I want to get this finished and out of the way as it's really starting to get me down, annoyed, fidgety and sad :( The base units been sat in the corner for ages.

[carlsson]

Aaw.. bad luck. You're about to downgrade from DDR2 to DDR memory. The replacement motherboard appears to be of slightly older vintage (!) than the broken one. A few motherboards have memory slots for both types of memory, but only one type at a time.

[bbcmicro]

Curses!
I assume that's bad...:)

BTW, the sticker says

512MB 1Rx8 PC2-4200U-444-12-DO
512MB, DDR2, 533, C14

not

512MB 1Rx8 PC2-400U-444-12-DO
512MB, DDR2, 533, C14

My mistake.

[carlsson]

Short off-topic lesson in how the most common DIMM modules are labeled today:

DDR-266 = PC-2100 (extinct since at least two years ago)
DDR-333 = PC-2700
DDR-400 = PC-3200
DDR2-533 = PC-4200
DDR2-677 = PC-5300 (or PC-5400 ?)
DDR2-800 = PC-6400

Apart from these, there are a few more uncommon ones. DDR-400 supposedly means the memory operates at a 400 MHz frequency. Off-hand I don't know what the number in PC-3200 is supposed to mean. DDR2 is (better at?) dual channel, so it should be faster.

Back to your question, the cheapest 1 GB DDR-400 (PC-3200) memory module on ebuyer.com is £55 incl. VAT. Add £3-7 if you want a brand name. You should probably not have to pay more than £70 even at a local store. For comparison, the cheapest 512 MB DDR2-533 (PC-4200) modules they sell are £28 each, or c:a £36 each for a brand name. Roughly speaking, if anyone offered you a straight swap, it would not be unfair.

[chuckcmagee]

The 4 digit numbers are the "number of bits per second" that you can read data out of the ram chip. 266 * 8 about equal 2100, etc.

[carlsson]

Thanks. It makes sense, now when you explained it. Using the same notation, an old PC-66 SDRAM should really be PC-500 while a PC-133 should've been PC-1000. BTW, I think I made a typo above: DDR2-667.

For bbcmicro's sake, I hope all the motherboard settings and installed drivers in Windows will remain the same despite that the two boards seem to use different memory technologies. Or at least that the system restore disk (if one exists) will work with this motherboard as well.

[bbcmicro]

I did think of that, but I was planning to dual boot Ubuntu anyway.
If windows decides to go into shock on me and needs a new install, (OEM install, no disks D: D: ) I'd rather not say how I'll deal with that ;)