memory/board issue - 1GB PC2700 in T40

[rook]

hi

i was searching on forum, but i can't find answer.

why in T40 2373-72U my 1GB PC2700 CL 2.5 module don't work?
system not booting, i'm getting 4 x 4 short beeps, mixed with branded IBM 256MB PC2100 CL 2.5

but in T40 2373-8CG that same 1GB memory works ok, also mixed with 256MB PC2100.

rook

[Pingwin Wielki]

Does your 2373-72U and 2373-8CG use exactly the same 256MB memory module (the same producer, the same model, the same version?) ?

Some memory modules don't like to work with another models. Please try to swap 256MB modules between both laptops and try again... Now you will probably notice that the other laptop "beeps" while the first one works OK.

And one more thing... You mixed PC2100 RAM with PC2700 RAM in the same machine, right? Not the good idea! You can search Google for more information about memory timings (T(RAS)+T(RCD)+T(RP)+CASLatency).

Memory timings for PC2100 are different than for PC2700, so the "longest cycle chain of them all" will dominate. However the memory bus works with constant speed (speed proper for slower memory modules - PC2100), so PC2700 may slow down your ThinkPad.

[rook]

i'm moving both modules 256MB PC2100 and 1GB PC2700 from 8CG to 72U, in 8CG they works, in 72U they are not.

ofcourse alone 256MB PC2100 works ok in 72U.

Memory timings for PC2100 are different than for PC2700, so the "longest cycle of them all" will dominate. However the memory bus works with constant speed (speed proper for slower memory modules - PC2100), so PC2700 may slow down your ThinkPad.

afaik T40 has PC2100 native memory bus, PC2700 is compatible down, so this should work.
PC2700 should work with speed of PC2100, i'm wright?

question is, why in one TP, mixed PC2100 + PC2700 works, in other not?

[Pingwin Wielki]

What about BIOS version in both ThinkPads? Are they the same?

Please check for "BIOS Version" and "Embedded controller version". Maybe your notebook needs firmware upgrade.

[Pingwin Wielki]

PC2700 should work with speed of PC2100, i'm wright?

Yes, of course. PC2700 will work with the speed of the PC2100 system bus.

The trick is the different timing written in memory module SPD chip. Let's assume that PC2700 will have a 8-3-3-3 timing, while PC2100 will work with 6-2-2-2 timing. If you connect those modules to the same system bus speed, the PC2100 will work faster.

However if you mix both memory modules in the same laptop, it is highly possible that BIOS will choose the slowest timing of them all (eg. 8-3-3-3) for the whole RAM system, thus slowing down the overall memory performance.

Unfortunately, ThinkPad doesn't offer you any BIOS option to set up memory timings manually or tweak it. It only accepts timings defined in SPD. That's why mixing memory modules of different standards is not the wise idea.

[rook]

i tried 1GB PC2700 alone, in 8CG it works, in 72U not.

propably systemboard in 72U TP is to old for this type of memory.

what is best i can do ?
buy PC2100 1GB module for 72U ?

[Pingwin Wielki]

First, try to check the BIOS version as I mentioned before. Maybe the firmware upgrade will help.

If it doesn't help, it would probably be the best to buy 2 x 512MB PC2100 memory modules. Yes, the 256MB module will become useless, because there are only 2 memory slots on the motherboard. But you can use it to upgrade the other ThinkPad.

Some ThinkPads had problems with 1GB modules indeed, but I don't remember exact model numbers.

[GACrabill]

I am typing this reply on a 2373-72U with a 1GB PC2700 stick and the original 256MB PC2100 stick. This 1GB PC2700 stick happens to be a Kingston module. I previously had a different brand of 1GB PC2700 in it and it worked fine also (I put that one in my daughters laptop later since I have 2 of the Kingston 1GB PC2700 sticks but only put one into my laptop so far).

Pingwin Wielki is correct ...... make sure that the BIOS is updated on the 2373-72U.

[rook]

i brought today 1GB PC3200 module, and it works!
i don't know why 1GB PC2700 won't work, but now it doasn't matter.