type of ram for X21/X22

[skanky]

ive got a stick of 256mb ram that's being used in a X21 i have (which works perfectly fine), trying the same stick in the X22 just results in a black screen on bootup.

it doesnt even get to the IBM logo, just hangs on a black screen. are the RAM types compatible?

[bhtooefr]

FRUs are different... (subtract one for option numbers, but FRUs are cheaper from what I've heard)

The X20/21's 256MB module is FRU 33L3070, whereas the X22-24's 256MB module is FRU 19K4655.

33L3070 is described as: "3.3 Volt, 144-pin, non-parity, 64-bit, 100 MHz SDRAM memory"

19K4655 is described as: "3.3 Volt, 144-pin, non-parity, 64-bit, 133 MHz SDRAM memory"

I guess it NEEDS PC133 to run... I don't know if a dirt-cheap stick will work or not... If not, you'll have to get a stick for an X22...

[skanky]

thanks.

[stevech]

X20-21 uses high density memory chips (8 components each side, and more expensive), whereas X22-23 uses low density (4 components each side, significantly cheaper). In my experience, the crucial factor is the density and not the bus speed, ie, PC133 should work in PC100 (and 100 in 133) as long as the density is correct.

[bhtooefr]

However, I'd use 133 in a 133 system, if only because all RAM runs as fast as the slowest RAM. In other words, RAM speed will slow to 100 if you use 100 in a 133 system (e.g., a X22)

I HAVE seen some sites selling 133MHz modules for an X21, so I wasn't sure about whether the X21 actually HAD to have 100. Thanks for the info, though...

As for your X22, get something like this: http://www.newegg.com/Product/Product.a ... 6820211124

It's a 4-chip 133MHz 256MB SODIMM. One reviewer actually tried it in an X23, so it should work in an X22 (IIRC, they use the same basic motherboard).

(It's what I almost got for the X21 I'm getting, until I saw this: "Will not work with my IBM Thinkpad t20, which requires pc100 ram. I could get it to boot, but as soon as it hit the windows screen, it restarts over and over again.")

[JHEM]

X20-21 uses high density memory chips (8 components each side, and more expensive), whereas X22-23 uses low density (4 components each side, significantly cheaper).

You have those backwards, 8 chips per side is lo-density and 4 chips per side is hi-density.

Yes, on most early thinkpads the memory density is more important than memory speed (PC100 vs. PC133). But lo-density PC133 memory is extremely rare.

Regards,

James

[dmdsoftware]

Yes, on most early thinkpads the memory density is more important than memory speed (PC100 vs. PC133). But lo-density PC133 memory is extremely rare.

Yes, it's very very very rare. From all the PC133 sticks I've seen, all are hi-density.

Therefore, the notion "you can stick PC133 in place of PC100 and it will slow down to 100" is totally incorrect. I see small shops suggest this all the time, and when I challenge them to demonstrate this working, they end up proving my point.

[bhtooefr]

In the context of a ThinkPad, you're right, dmdsoftware.

However, in a system that supports x type of RAM, and you have a stick of x type running at 100MHz, and a stick of x type running at 133MHz, you can put them in, and they'll both work, but they'll both run at 100MHz. We can use my crappy old (and now completely torn apart - the parts are in about three different computers) HP system as an example. Noname 128MB PC100 SDRAM stick in slot 0, PNY 128MB PC133 SDRAM stick in slot 1. Both ran at 100MHz.

A ThinkPad X21 (for example) uses "a" type memory (for this example). On the motherboard is a "stick" of either 64MB or 128MB PC100 of "a" type. It has a SODIMM slot. You can put a stick of "a" type memory from 64MB to 256MB. If you put a PC133 stick in (I've seen exactly one), it'll run at PC100. If you put a PC100 stick in, it'll run at rated speed.

A ThinkPad X22, on the other hand, uses "b" type memory. The motherboard has 128MB of "b" type memory at 133MHz. A PC133 stick of "b" type (from 64MB to 512MB) will work normally. A PC100 stick will slow the on-board memory down to 100MHz. A stick of "a" type simply won't work.

Sorry about the long post, and I'm sure some of you already know all of this, but I'm just clarifying a point

[aceo07]

Sorry for bumping this up. Based on some of these posts, is it true that I NEED to use 'high density ram' for the X22?

I tried low density 512MB with it and it didn't boot or beep.

[bhtooefr]

What are the specs on that memory? Edit: Just to make things clear, "low-density" means 8 chips on each side of the module, for a total of 16, and "high-density" means 4 chips on each side of the module, for a total of 8.

FWIW, just to throw some anecdotal evidence in the pile...

I just serviced a Panasonic Toughbook CF-48 (Pentium III model (this particular one had a 900MHz CPU) - there's also a P4 model). It was running Windows XP with only 128MB RAM.

So, I recommended a 256MB PC133 CL3 high-density stick of Kingston on Newegg. I install it, and it only sees 256MB (much like the Type 2662 X2x laptops, it had 128MB soldered to the mobo).

I then try my 256MB PC100 CL2.5 low-density stick of Kahlon crap that's in my laptop. Works like a charm, sees all 384MB.

Looks like it's time to find one of those elusive PC133 low-density modules.

[aceo07]

I got my 512MB today and it works fine. Kingston 512MB PC133.

I used to only have 128MB and was running WinXP. It pretty decent.

[ephem]

Ace, was your chip similar to this one?
http://www.i-tech.com.au/products/5276_ ... PC133_.asp

I don't want to buy it and it doesn't work.

Thanks mate.

[aceo07]

The ram I bought was: http://www.zipzoomfly.com/jsp/ProductDe ... e=80316-SO

It installed and works fine. I just wish old laptop ram wasn't so expensive compared to the new stuff.