Upgraded RAM

[priyansh]

Hi All,

I have T41 model and I just bought the 1GB RAM PC2700 from Lenovo. Initially my model had PC2100 512 MB ram as primary ram which runs at about 220 Mhz. When I install the new 1GB RAM it also works at about 220 MHz. I am now confused. Should I remove the primary 512MB ram as it is slowing down the new ram also and use the 1GB only at 333 Mhz or should I go for 1.5 GB of ram working at 220 Mhz?

Your views will help a lot

[kam_]

It depends! (PC2100 = 266Mhz, PC2700=333Mhz)

But i would probably run 1.5GB at the lower speed. The extra 66Mhz isn't going to make as much difference as 512mb in windows - asuming you're using windows?

[cmarti]

Remove the 512 stick and see at what speed runs the 1gb stick it is supposed to run at 266mhz because of the motherboard, but who knows? maybe it will be running at 266 because of the 512 stick and when you remve it the 1gb stick will run at 333mhz.

worth the try!

[dash7540]

Right, the speed the RAM runs is dependent upon the mainboard; if it only supports DDR266 RAM, then putting in a DDR333 won't make it run at it's rated speed (333MHz), instead, it will go downclock to 266MHz.

Since memory bandwidth in notebooks is quite limited to begin with, it's recommended that you just keep the full 1.5GB in - general performance will still be greater with 1.5GB at 266MHz than 1GB at 333 (again that's assuming your mainboard supports it, which I don't believe since it shipped with 266MHz RAM.)

[XCoalMiner]

How are you viewing at what speed the memory is running? Have been looking for a way to determine this.

[dash7540]

XCoalMiner,

There are a number of diagnostic/benchmark/system information programs such as Futuremark's PCMark, SiSoft's SANDRA, etc. that will tell you what your memory speed is, but probably the easiest way is to use CPU-Z http://www.cpuid.com/cpuz.php; it's a very tiny program that tells you quite a bit about your CPU/mainboard/memory.

[kam_]

Odd my Dothan shows as running dual channel, but 266Mhz

Also its not showing any info from SPD. Is it just because it can't read the controller in the thinkpad, or SPD isn't even working?

[XCoalMiner]

I also have a question on what CPU-Z shows. Where's a good place to ask, in this thread, start a new one, etc.?

[lithium726]

Post here, i can probably field it

[lithium726]

Odd my Dothan shows as running dual channel, but 266Mhz

Also its not showing any info from SPD. Is it just because it can't read the controller in the thinkpad, or SPD isn't even working?

If its not saying anything SPD, thats probably the issue. The bus itself is working at 266mhz (133x2 for memory, 133x4 for 533 on the processor), the memory however should be running dual channel with a 4:5 divider making it run dual channel 333mhz. Otherwise its running a 1:1 divider for some reason.

[XCoalMiner]

Post here, i can probably field it

Thanks.

Have a T41. Just replaced the original 256 Mb memory module that came with the system (the one under the keyboard) with a DDR PC2700 1 Gb module from Crucial. Previously (two years ago) added a 512 Mb module in the open slot, the one accessible from the bottom (also Crucial brand).

Thought both modules run at 333 MHz. But CPU-Z shows app. half that speed - In the Memory tab, Timings > Frequency says 166.1 MHz. And in the SPD tab, for Max bandwidth, when select either slot 1 or slot 2, the Max Bandwidth shows as "PC2700 (166 MHz)". The SPD Timings Table > Frequence shows 133 MHz (slot 1 I guess) and 166 MHz (slot 2). Am I missing something, shouldn't the memory be running at 333 MHz.

Also, another oddity. The 512 Mb module I added two years ago was from Crucial, but CPU-Z reports it as from Infineon. Maybe I manufactures for C, not certain?

[dash7540]

Oh yeah, I forgot to mention that the memory speed shown by CPU-Z isn't reflected as DDR, so for example the 166MHz that XCoalMiner is seeing is actually correct. (166 x 2 = 333)

Now as for the one that says it's 133MHz, it's possible that (I'm guessing it's the 512MB stick) you might've gotten PC2100 (133 x 2 = 266MHz) RAM instead of PC2700?

And as for the manufacturer discrepancies, if I remember correctly IBM/Lenovo's stock memory is made by Infineon, but since you said both sticks were from Crucial, I really can't say why CPU-Z would report it as Infineon (unless it's true that Infineon manufactures for Crucial...)

[XCoalMiner]

Ok. Figured it was something like that, but wanted to know for sure.

That 133 MHz speed is still a curiosity. It's only reported as 133 MHz in one place, in the SPD Tab in the lower frame for SPD Timings Table, the first column shows Frequence of 133 MHz (second column shows 166). Everywhere else it's reported as 166 MHz, (it also says PC2700 for both modules). Unfortunately the slot reporting 133 is the new 1Gb Module (which I just got from Newegg, and was marked as 2700, but now I might take the keyboard off and verify what I remember).

[lithium726]

Can you post a screenshot of the CPUZ screen youre looking at? It would help immensly

[XCoalMiner]

Can you post a screenshot of the CPUZ screen youre looking at? It would help immensly

Thumbnail screen shots below, click to enlarge, (unfortunately, couldn't get all five images to display full size simultaneously). An album is here.

CPU Tab


Memory Tab:


SPD Tab, Slot 1


SPD Tab, Slot 2


About Tab, for version

[lithium726]

OH - now i get what you are saying. What that is is a table embedded in the DRAM called the SPD table... basically, when the system asks for 133mhz, the DRAM will run at those timings. When the system asks for 166mhz, it will run at the timings listed. If your ram were capable of PC3200 (DDR400) you would see that on the table as well with its associated timings.

Your memory is running at 166mhz though.

[XCoalMiner]

Your memory is running at 166mhz though.

As opposed to 333 MHz?

And a follow up question. Why would the system request the memory to run at 133 MHz, when the processor is running at 1600 MHz, the bus (that gets data to the memory controller) is running at 400 MHz, and the memory is running at 333 MHz? Even if the processor slowed to 1200 or 900, it would still be faster then the bus and the memory. I'm guessing the answer has something to do with latency, but guessing is the key word, it's unknown territory to me.

[lithium726]

166x2=333mhz. The memory itself is running at 166mhz but it carries two bits per clockcycle, as opposed to the 1bit of previous SDRAM. It is rated as "333mhz" because it has the throughput of 333mhz SDRAM

Now then, on to your other question...

Your system is running at a base clockspeed of 100Mhz. Your processor is on a quad-pumped data bus to the northbridge, which is 400mhz. You acheive the clockspeed of 1600mhz by multiplying the base clock (100mhz) by 16. The memory speed is based on dividers. In a typical system, memory will be run 1:1. This is the most basic setting - so, if your memory were running 1:1 with the bus clock of the system, it would be running 100x2 = 200mhz, PC1600 (you always multiply by two for DDR). However, the T4x series uses a divider to RAISE the memory speed to give a higher bandwidth throughput from the CPU to the memory. So, in your T41's case, it uses a divider of 3:5. That will give a system clock of 100mhz and a memory clock of 166mhz (PC2700) (33x3 - 100, 33x5 = 166). The T40, for example, uses a divider of 3:4, which puts the system clock at 100mhz and the memory clock at 133mhz, or PC2100.

Then your northbridge communicates with your southbridge through a proprietary intel bus for I/O. Your AGP, PCI, USB, ect is all controlled from the southbridge which commincates with the CPU through the northbridge. On Intel platforms, the Northbridge is the only chip on the board which commuincates directly with the CPU.

On a T40 system, the board will request 133mhz. On a T41 or T42 it will request 166mhz. On a real old P4 system it will request 100mhz.

[XCoalMiner]

Thanks lithium. Very enlightining. Now I'll have to read up on some of these things, when I get the time.