Will IBM Thinkpad A21m use PC133?

[MotherGoose]

Maybe a dumb question, but I need to upgrade my better half's Thinkpad A21m, and 256mb PC100 SODIMM memory is $119.99, while 256mb PC133 is only $69.99 (retail store). Faster is better, right?

 

[jpeyton]

They are backwards compatible, so the PC133 would run at PC100.

 

[MotherGoose]

I guess some other brand than PNY, then, which is the cheap "off the shelf" price mentioned above.
This from a dealer web site: "Important Notice From PNY: PC133 Modules are NO LONGER backward compatible with PC100 Machines. "

 

[jpeyton]

The non-backwards compatibility may have to do with the fact that newer SDRAM modules were often high-density modules, while many PC100 and some PC133 chipsets only recognized low density modules.

 

[Epsil0n00]

I have experience supporting over 60 IBM ThinkPad A21m laptops at my organization. The A21m is very picky about what kind of RAM you install. I attempted a while back to purchase and install 2 256MB PC133 SODIMMs from Crucial and they did not work. The A21 just beeped at me... I tried it in another A21m to make sure and that one beeped too.

In most cases putting PC133 in a unit that usually takes PC100 is just fine. In the A21m you have to have PC100... and to complicate it even more it has to be low density (which most PC100 RAM should be...). Now I only purchase RAM for A21m laptops from IBM directly or from Crucial. It is a lot more money, but Crucial, IBM and my testing all confirm that PC133 will not work in A21m laptops.

Sorry to break the bad news to you!
Good luck!
Epsil0n

 

[MotherGoose]

Thanks, Epsil0n. I kind of suspected it, having worked for IBM services about a decade ago, and having seen how difficult it was then to find compatible hard drive upgrades for their ATM's at the time. Seems like they end up shooting themselves (and the true believers) in the foot with all the proprietary stuff (Where is OS2 now?)

Probably better to stay true blue in this case... Gives me the blues, though!

 

[DaFinn]

I can confirm, A21m is VEERY picky about RAM. Go to Kingstons page for example and order compatible ram through them... I tried 3 different brands and types in my old a21 before I gave up.

 

[tcsenter]

The A21m is very picky about what kind of RAM you install. I attempted a while back to purchase and install 2 256MB PC133 SODIMMs from Crucial and they did not work. The A21 just beeped at me...

Its not that A21m is 'picky' about RAM, you have to install RAM that is compatible.

A21m uses the Intel 440BX/ZX chipset, which does not support the use of DRAM components higher than 128Mbit technology. Most (virtually all) PC133 modules in the last couple years are made with 256Mbit DRAM components = no workie on older PC100 era chipsets. PC133 no matter the components will work fine @ 100MHz operation.

The A21m requires a 256MB module with a total of 16 DRAM chips, 8 per side.

128Mbit x 16 chips = 256MByte
256Mbit x 8 chips = 256MByte <-- not compatible

These are fairly plentiful on Ebay; going price is about $60 ~ $70 shipped, sometimes as low as $50 and as high as $90. I purchased two 256MB modules to max-out an A21m Thinkpad I had a few months ago (sold it). Look for modules that have 16 chips total. Don't go by the photo, many sellers use one photo for different types of RAM.

You can cross-reference other makes and models that require the same memory specifications:

Dell: Inspiron 2500, 3700, 3800, 4000, 5000, 7500; Latitude C500, C600, C800, CPt C-Series, CPx
Toshiba: Satellite 1800, 1805, 2805, 3000; Tecra 8000, 8100; Portege 7140CT, 7200CT, 7220CT,
Compaq: Armada E500, E700, M300, M700
HP: OmniBook 500, 900, 6000, XE3C
IBM: Thinkpad 390X, 570E, 600E, A20m, A20p, A21e, A21p, A22e, A22m, A22p

Or you can cross-reference part numbers:

IBM # 33L3069 and 33L3070
Kingston # KTD/KTM-INSP7500/256 (Dell), KTD/KTM-TP390X/256 (IBM), KVR100X64SC2/256 (Kingston), KTT-SO100/256 (Toshiba)

This Ebay seller is a consistent source for these modules. I am not endorsing this reseller and I've never purchased from him. But I've bid [unsuccessfully] on a dozen of his auctions and it appears this is the only kind of 144-pin 256MB module he sells for notebooks (with 16 chips).

Any of these will work (not an endorsement of any Ebay seller):

256MB SODIMM for Thinkpad

Samsung 256MB 144 pin 16 chip PC100

256MB SODIMM for Thinkpad

 

[WobbleWobble]

I'll concur that the A series is very picky. We tried 6 different sticks of RAM and our A22m wouldn't take it. It would only take RAM that seemed to be 3x the price (back then).

 

[bleuless]

not meaning to hi-jack the thread, but i am having problems with my a21m right at this moment, please bear with me, sorry and thank you. please just let me ask my question, and i'll take it in the PMs if you guys think this is necessary.

my a21m has been faithful to me for a few years now, but i've been having problems with it freezing randomly and now it seems to get worse. I did notice a few interesting observation.

1. if it locks up, its almost guaranteed to lock up again during boot (of windows xp) if you power cycle it immediately. (seems heat related? but this is very random and i doubt is over heating, sometimes it "acts up" immediately in a fresh cold morning)

2. i can always boot up fine in safe mode, say i am constantly locking up for the past 10 tries, and i boot into safe mode and it works, go back to normal, and no good.

3. if i let the lap top sit for a while, few hours, sometime over night, and try it again tomorrow, it probably will works again normally as if nothing ever happened.

i am currently running windows xp sp2, with 192 ram, 128 is stock, 64 is add on. i tried switching them, taking 1 off, etc, doesn't seem to be the ram. i updated the bios to the latest, updated the hdd firmware to the latest. the next thing i can think of is the video card driver, or module.

any suggestions? thanks.

 

[DaveSimmons]

It could be a driver issue, trying to start a device and failing. Hmm, does/can XP still create bootlog.txt like win9x?

Have you tried a format and fresh install of Windows?