Confused: PC2700 or PC3200 sodimm RAM for new Thinkpad T42?

[IBMorBust]

I'm a little confused here.

Should I buy PC2700 (DDR333) memory or PC3200 (DDR400) memory for my new dothan 1.6 centrino T42?

It's my understanding that the T42 has a 400MHz FSB, so won't the PC2700 RAM slow the system down?

Shouldn't I use the PC3200 (DDR400) RAM to maximize the potential of the system speed?

[RonS]

You should buy PC2700. You won't realize any perfomance difference by going to faster memory.

FTI, my T42p came with 1GB of PC2100 memory (CL2.5) I bought another 1GB of memory from e-bay for $180, and it works perfectly.

[IBMorBust]

But if PC3200 memory would work at the faster 400 FSB rate:

1) Why would IBM ship with slower PC2700 RAM?

2) Why wouldn't one want to take advantage of faster rate?

3) Wouldn't adding faster RAM in addition to slower standard PC2700 RAM handcuff the additional RAM (drag the additional RAM down to standard PC2700 RAM speed)?

[IBMorBust]

Anyone else care to weigh in?

This is an interesting issue to me and one that I welcome everyone's feedback on.

Thanks.

[IR0NMAN]

The system bus on centrino laptop is 333mhz , so you cannot run DDR400 (which need a 400MHZ bus)

If you put DDR400 on a 333mhz laptop, the DDR 400 will go down to 333mhz automatically but i'm not sure about this.

The only way to run DDR400 on a laptop is to overclock your bus to 400mhz

[fargusmax]

The chipset doesn't support anything faster than PC2700. So, paying any premium to get PC3200 is a waste. I just wonder if we can get PC2700 at CAS 2, instead of the usual CAS 2.5, to work. That'd be great.

[RonS]

My brand new T42p came with 1GB of PC2100 memory (according to the packing list). Does that mean that my system is underperforming?

[RonS]

The system bus on centrino laptop is 333mhz , so you cannot run DDR400 (which need a 400MHZ bus)

Nope - Centrino bus speed is 400MHz.

See this link: http://www-307.ibm.com/pc/support/site. ... 751#pc2100

[tofutti]

The system bus on centrino laptop is 333mhz , so you cannot run DDR400 (which need a 400MHZ bus)

Nope - Centrino bus speed is 400MHz.

See this link: http://www-307.ibm.com/pc/support/site. ... 751#pc2100

you're right. but i think he meant to say the memory bus speed is 333mhz. dunno tho. (edit: o he did mean to say what he said)

did that 1gb of pc2100 come from ibm/refurbished/ebay? (edit: the 1st 1gb)

i'm pretty sure all 42's are supposed to have 2700.

in anycase 2700 will perform better.

[daeojkim]

The memory bus speed for Centrino cannot be higher than 333 MHz due to the chipset that supports Centrino. The CPU bus is 400MHz, but since the chipset only supports 333MHz memory bus, using a 400MHz memory will not change anything.

If you are using a 266MHz (DDR2100) then yes your system is under performing. Check your RAM and make sure that it is not DDR2100. If it was directly from IBM I doubt they would have put DDR2100 instead of DDR2700.

[fargusmax]

It's not 2100. I called with the intent of complaining bigtime when I saw the PC2100 listed on my 2373-KTU. They assured me it was a typo, that it was in fact PC2700.

[RonS]

It's not 2100. I called with the intent of complaining bigtime when I saw the PC2100 listed on my 2373-KTU. They assured me it was a typo, that it was in fact PC2700.

The exact same thing just happened to me. I spent the last 1/2 hour on the phone with IBM, and I ended up removing the keyboard to look at the memory module. Sure enough, PC2700 CL2.5. There's an error on their PartsLookup page that incorrectly says PC2100.

The rep said that PC2100 memory was last used in the T40 systems. T41 and T42 uses PC2700.

[IBMorBust]

Okay, daeojkim, thanks for clearing that up.

Unless anyone dissents, I'll assume that is correct.

I hope others had any issues resolved or benefitted from my question.

Thanks again.

[rhobite]

If you're confused about what type of RAM you're using, no need to rip the Thinkpad apart. You can run CPU-Z and find out exactly what type you have, in addition to good stuff like bus speeds and CPU core type.

[RonS]

Great tip! Direct link: http://www.cpuid.com/cpuz.php

[Leon]

Good find rhobite & Ron!

also, after much debate on this board about "quality" memory, cpu-z tells me mine (from IBM) is Mosel!

me thinks I'll just order this for additional

thanks treker, from the link below

[treker]

Leon,
That NewEgg link is for desktop PC memory. T42s need 200pin PC2700 SO-DIMM. It costs more. I love The EGG, too. I have used Rosewill PC2700 SO-DIMM in another laptop - it worked fine.

Try this link: http://www.newegg.com/app/ViewProductDe ... 013&depa=0

Treker

[IBMorBust]

I received my T42 today. I installed an extra stick of Kingston 512MB RAM. Took 1/2 a minute and runs like a champ.

Unfortunately, other quality control issues plague my T42. Sigh.

[wdub]

Is some power consuming issues in discussion 2700 vs. 3200 ?

[cruzlite]

Thanks to Rhobite & RonS for the link!...
cpu-z reads my factory memory (under SPD tab):

Slot #1 DDR-SDRAM
512mb
(Max bandwidth) PC2700 (166mhz)
Samsung

SPD Timings Table
FREQ................133mhz...166mhz
CAS# Latency...(2.0)........(2.5)
(I expected to see 333mhz)...

Crucial tool gives me PC2700/DDR 333

Won' the IBM(Samsung) handcuff the crucial down to 133mhz?
what am I missing here?

[Herr Yunta]

The timings table are what the memory is capable of, the memory is going to run at 133MHz regardless due to the chipset.

[revolutionary_one]

Just a little extra on the topic. Yes the centrino chipset only supports a memory bus speed at 333, but even if you were to stick in a dimm rated at 400, you wouldnt feel any performance diference.

However, if you found a decent deal on ddr400, you obviously should go a head and get it b/c you can probably use it an another laptop that supports ddr400.

Also, incase you were wondering, even IF you have a laptop that supports ddr400 on the memory bus, if you stick in two sticks, with one ddr333 and one ddr400, the bus will still run at ddr333, b/c the bus is only as fast as its slowest dimm. This applies to desktops as well.

Buy wisely, kudos on a decent question

[Herr Yunta]

I would take that advice with a grain of salt. Not all memory is backward compatible or will play nice or even run at all with memory of different speeds. It is best to buy the memory designed for your particular machine.