Interesting PC133 512MB modules

[rkawakami]

Most of you know that I'm still in the process of building up a T23 army . Some of you also know that I don't like paying for memories that I could have had for free many years ago. To that end, I'm always looking for cheap PC133 512MB modules on eBay. I ran across something these past couple of weeks that was interesting and since the seller appears to have run out ( ), I'm posting this info now.

I use various search terms to unearth eBay listings which may have been overlooked by others. I spotted one that I had seen before but at that time I didn't research it enough to know what it really was. This time there was enough information in the auction description that convinced me to give one a try. They don't look like "regular" modules in that they use what's called "chip-on-board" (COB) packaging. This is where the silicon die is glued directly onto the module's PC board and then encapsulated with plastic. Most of the time there's no part number or familiar brand name on these modules. The ones I've found look like this:

http://www.kawakami-ca.com/images/silic ... _512mb.jpg Silicon Mountain SMM13375-24299

Googling that part number leads nowhere. It does not appear on the Silicon Mountain website. I took a chance and bought one. Works perfectly inside a T23. Brought it to work and looked at the manufacturer information in the SPD bytes and extracted a Swissbit ( ) part number. Found a datasheet for it and it says that there's Micron die inside those modules. Apparently Swissbit had bought known good die (KGD) from Micron and Samsung and then assembled the modules. The main reason why module people use KGD is for the lower cost. The normal route for module assemblers is to buy packaged parts and solder them onto the board. With KGD you do not have to pay for the package cost for each one of the 16 chips that go on a "standard" PC133 512MB module. Of course there's the added difficulty in the COB assembly process but that's more than offset by the savings in package costs.

I'm in the middle of setting up a web site to document what I've found with these modules. I'll post the URL here when it's ready. I've already shipped out the first module in trade for some PC100 256MB so I'm waiting for the remaining modules to arrive before finishing the web site.

So, now I'm probably going to have some competition on eBay whenever these modules show up. Don't forget that I snipe!

[pianowizard]

How cheap are these modules? $20 apiece?

[rkawakami]

$26 shipped. However, that's only because I bought two or four at a time and the seller offered combined shipping. The first one was $24 with $5 shipping. Not too bad when you consider people are still paying upwards of $50 on eBay for these things.

[rkawakami]

I finally received the balance of the shipment and verified that they all work. As promised, here's the web site I set up with some details about this memory module:

http://www.kawakami-ca.com/swissbit_module/

I do have to note that I received an almost identically constructed module tonight from a different eBay seller and it had a different label. This one said:

"Lifetime 512MB PC133-333 SSN06464P2B32MT-75"

It fails memtest86+ for two output pins. This one may be a write-off since the seller (dealexpress) does not accept any returns and instead directs you to the manufacturer. Well, supposedly these were made/sold by "Marlow Data Systems" and I'm sure that they don't exist anymore. Doubtful that I can get Swissbit to accept a return on this but I still might contact them and see what they say. I'll also try getting a scan of it posted on the page I linked to above.