Does Slower RAM Stick Slow Down Faster One?

[jimwg]

Greetings!

I'm receiving a second-hand T400 Intel C2D P8600 that has 2gigs RAM onboard (unknown type or speed but I assume basic 1066Mhz) . I have an opportunity to install 4GB (DDR3 PC3-12800, NON-ECC, ) in it. Amazon users say this buy is a faster chip and mixed well with slower preinstalled chips. My question is is it okay to "mix", and further, do slower memory chips force the CPU to throttle down faster chips in order to "sync" or use them, so should I just leave out slower chips to maximize speed?

Thanks for any advice!

Jim in NYC

[dr_st]

You can mix slower and faster RAM, but it will run at the speed of the slower one. The actual performance difference will be negligible in any case.

[jimwg]

You can mix slower and faster RAM, but it will run at the speed of the slower one. The actual performance difference will be negligible in any case.

Thank you for your swift reply!

When you say negligible, then is there any real noticeable advantage to having "faster" RAM at all, or is it really more a marketing "faster-better-pricier" gimmick?

Thanks!

Jim in NYC

[ajkula66]

Two things here:

1) T400 - and related models - are known to be picky about RAM. There's an excellent chance that the machine will outright refuse to boot with faster RAM.

2) You'll lose "full" dual-channel capability by running RAM sticks of different speeds. Not that it matters a bunch on an older system.

I'd go with DDR3 in the original speed, from a known manufacturer, skipping "value RAM" and "no name brand" offerings, but that's me.

[thinkpadcollection]

DDR3-1333 and 1600 will work in this one. I had that 1600 in a T500, yet still running at 1066 fsb.

Cheers, thinkpadcollection

[kfzhu1229]

It doesn't really matter since this machine utilises the slowest DDR3 speed. If you throw in anything faster than the stock config it will still stay the same speed

[ajkula66]

DDR3-1333 and 1600 will work in this one. I had that 1600 in a T500, yet still running at 1066 fsb.

Cheers, thinkpadcollection

Given that some of us have had different experiences, you may want to be specific and name what DIMMs *exactly* you're using so OP knows what to look for...

[thinkpadcollection]

Was Elpida or Micron 2Rx8 DDR3-1600 (16 chips each module) pulled from a old Mac that did not work right in newer machines using 1333 fsb. I needed to find a place for that pair and succeeded in T500. That happened once but I have good experience with any PC or Mac modules from ebay in my herd of machines.

Cheers, thinkpadcollection

[jimwg]

VERY helpful dialogue! So my non-techie reading of this is that my T400 is actually better off in terms of speed and performance if I remove the preinstalled (slower?) 2gig memory stick and let the new 4GB (DDR3 PC3-12800, NON-ECC) stick do the job by itself?

Thanks for the education!

Jim in NYC,

[bit_twiddler]

You're almost always better off with more ram, even if it is slower than the
top rated ram for the machine, because secondary memory (disk, ssd) is several
orders of magnitude slower.

[AIX]

I would not mix different size modules on T400, they are prone to this kind of visual corruption:

https://support.lenovo.com/ro/en/documents/ht001223

Type B visual corruption is a permanent limitation of the Intel chipset. There exists the following three options to work around this issue.

Option 1: Disable Virtualization Technology for Directed-IO (VT-d). This can be done in the BIOS setup utility. When the system is first booting (during POST), press F1 to enter the setup utility. Then enter the Config menu, and the CPU submenu. Change VT-d to disabled.

Option 2: Make sure that there is only one memory DIMM in the system.

Option 3: Make sure that the two memory DIMMs in the system are of equal size. For example, both are 2GB.

[ajkula66]

I would not mix different size modules on T400, they are prone to this kind of visual corruption:

https://support.lenovo.com/ro/en/documents/ht001223

Type B visual corruption is a permanent limitation of the Intel chipset. There exists the following three options to work around this issue.

Option 1: Disable Virtualization Technology for Directed-IO (VT-d). This can be done in the BIOS setup utility. When the system is first booting (during POST), press F1 to enter the setup utility. Then enter the Config menu, and the CPU submenu. Change VT-d to disabled.

Option 2: Make sure that there is only one memory DIMM in the system.

Option 3: Make sure that the two memory DIMMs in the system are of equal size. For example, both are 2GB.

While I'm aware of the article in question, I've never experienced this problem on a *00 series unit. YMMV.

I would, however, stick with the stock speed RAM produced by a known manufacturer...

[axur-delmeria]

VERY helpful dialogue! So my non-techie reading of this is that my T400 is actually better off in terms of speed and performance if I remove the preinstalled (slower?) 2gig memory stick and let the new 4GB (DDR3 PC3-12800, NON-ECC) stick do the job by itself?

Thanks for the education!

Jim in NYC,

I'm actually more worried of RAM compatibility, as it is a known issue when using newer DDR3 RAM on older laptops.

Since the T400 and X301 use the same Intel GM45 chipset, I believe that the user-compiled RAM compatibility list for the X301 on this page applies to your T400 as well.

[jaspen-meyer]

For what it's worth, here are ram modules I've run in a T400:

16JSF25664HZ-1G1F1
8JSF12864HZ-1G1F1
EBJ11UE6BASA-AE-E
EBJ21UE8BDS0-AE-F
HMT125S6TFR8C-G7
M471B2874DZ1-CF8
M471B5273CH0-CH9
M471B5273CH0-CK0
M471B5673FH0-CH9
M471B5773DH0-CH9

[blink]

[quote="AIX"]I would not mix different size modules on T400, they are prone to this kind of visual corruption:

https://support.lenovo.com/ro/en/documents/ht001223

Thanks for the heads up. I wasnt aware of this issue. I have to say i run most of my thinkpads T400 X200 etc on 6gb as i find this the optimal for my usage, (Very rarely need more than 4gb) & 8gb seems just wasted ram for my needs & i have never noticed an issue.

[SaskFellow]

2 sticks of the same size will always be faster than using 1 or by using 2 sticks of different sizes.

Reason is that dual or multiple channel ram controllers are basically the norm now, the ram controller has to logically assign the physical ram to the other channel, if its a more advanced controller. In a simpler controller it just runs in single channel mode.

An equivalent is like having two hard drives on a controller. In single channel mode it still uses two physical controllers but it runs them independently. Each drive is written and read to independently so the drives run at 64 bit each. In RAID 0 the drives are linked, so the data is split between them, they read and write half the data, so the 64 bit controllers act as if it's really a 128 bit controller, just like dual channel. The catch is that the drives have to be the same size, and the drives are limited by the slowest drive, so if you have a 5400RPM drive paired with a 7200RPM drive, the 7200 will sit idle while the other catches up. If you have two differently sized discs, you either lose the capacity difference or you run software that tries to make up the difference or you end up with two drives making a single amount of capacity that looks like a single disc but is running on each controller. Since the controller reads and writes to each drive independently, it can run faster than a single drive but that relies on the controller to put files on one or the other, so it's much more like a more efficient single 64 bit controller than giving you the performance of a true dual channel.

In summary or the TLDR and to simplify, faster to slower:

2 modules of the same speed + size, dual channel

2 modules of differing speed but same size, most likely to run dual channel

2 modules of differing speed, size, and/or both, most likely to run enhanced single channel, or software dual channel

1 module, will run at single channel speeds

The above is assuming that the system is a dual channel and two slot system. Single channel is 64bits, Dual Channel is 128bits, and the soft dual channel can behave like both.

This is all as simplified as possible for the non-technical among us.

[ajkula66]

2 sticks of the same size will always be faster than using 1 or by using 2 sticks of different sizes.

Simplistic and inaccurate statement. Try running (on the same machine) 2x1GB then install a 4+2 GB set and let us know whether you still maintain the same stands.

An equivalent is like having two hard drives on a controller.

No it's not.

In summary or the TLDR and to simplify, faster to slower:

2 modules of the same speed + size, dual channel

Correct.

2 modules of differing speed but same size, most likely to run dual channel

Debatable. At best.

2 modules of differing speed, size, and/or both, most likely to run enhanced single channel, or software dual channel

What you're referring to is usually called "asymmetric" or "asynchronous" dual-channel mode, which is only marginally slower than a full blown dual-channel. I've never heard anyone use the term "software dual channel", but I'm always open to learning new things...

1 module, will run at single channel speeds

Correct.

A pretty good thread on NBR showing all sides of the argument from a few years ago:

http://forum.notebookreview.com/threads ... ke.727936/

At the end of the day, most benchmarks will show that the differences in speed among any of these configurations are well under 5% - and I'm being generous here - which reflects the figure that most of us mortals will never be able to perceive in real life.

Having said that, all of my machines capable of running in a dual-channel mode are set up that way. A matter of preference, no more and no less.

[TonyJZX]

Arent all laptops of this era (ie. t400-420 all models) all ddr 1066? Ie. the slowest speed available? ie. 533mhz?

I have a mix of ram but always two sticks of the same speed up to ddr3 1600 and they all clock down.

I think this place has even dispelled the notion that ddr3L doesnt work.

I beleive it works in the 410/420 but not sure about the 400.

Also the 400 doesnt support spd which is a bummer.

[ajkula66]

Arent all laptops of this era (ie. t400-420 all models) all ddr 1066? Ie. the slowest speed available? ie. 533mhz?

No. *00 and *10 are, but not *20.

[TPFanatic]

I can't even tell the difference between DDR3-1066 running at full speed versus 800mhz speed with an 800mhz fsb T6570 in an R500.

[jimwg]

2 sticks of the same size will always be faster than using 1 or by using 2 sticks of different sizes.

Reason is that dual or multiple channel ram controllers are basically the norm now, the ram controller has to logically assign the physical ram to the other channel, if its a more advanced controller. In a simpler controller it just runs in single channel mode.

An equivalent is like having two hard drives on a controller. In single channel mode it still uses two physical controllers but it runs them independently. Each drive is written and read to independently so the drives run at 64 bit each. In RAID 0 the drives are linked, so the data is split between them, they read and write half the data, so the 64 bit controllers act as if it's really a 128 bit controller, just like dual channel. The catch is that the drives have to be the same size, and the drives are limited by the slowest drive, so if you have a 5400RPM drive paired with a 7200RPM drive, the 7200 will sit idle while the other catches up. If you have two differently sized discs, you either lose the capacity difference or you run software that tries to make up the difference or you end up with two drives making a single amount of capacity that looks like a single disc but is running on each controller. Since the controller reads and writes to each drive independently, it can run faster than a single drive but that relies on the controller to put files on one or the other, so it's much more like a more efficient single 64 bit controller than giving you the performance of a true dual channel.

In summary or the TLDR and to simplify, faster to slower:

2 modules of the same speed + size, dual channel

2 modules of differing speed but same size, most likely to run dual channel

2 modules of differing speed, size, and/or both, most likely to run enhanced single channel, or software dual channel

1 module, will run at single channel speeds

The above is assuming that the system is a dual channel and two slot system. Single channel is 64bits, Dual Channel is 128bits, and the soft dual channel can behave like both.

This is all as simplified as possible for the non-technical among us.

VERY educational! Thanks a million for this! You must be a teacher!

[SaskFellow]

Ajkula I was trying to simplify as much as possible. There are issues but for someone who doesn't know, its a good starting point. As such I really appreciate that you took the time to fill in and add some more details to my post.

What I meant by my 2 sticks > 1 bigger stick was a real poke at 2* 1GB will be faster than 1* 2GB. Of course 2*1 will get clobbered by a 1*4 set up for user life, but from a strictly performance standpoint until you run out of 2GB it'll be faster, then a lot slower. But there are diminishing returns.

I'm typing this on a Windows 10 tablet with a quad core Atom rocking 2GB of ram... I'm aware of ram limits and speed. In comparison I have a Sony YB33 with its AMD A series dual core, jumping it to faster ram had a noticeable impact on how the system felt, it was an interesting case where the RAM speed going up also increased the GPU test score along with RAM and CPU Scores.

My T61 with it's 2*4GB DDR2 800, can just do more and doesn't feel any faster, smoother yes, than my HP with it's 2*2GB DDR2 1066, honestly my T420s with its 2*8GB DDR3 1600, doesn't seem faster, I can just so more smoother. My 2GB x86 tablet boots the fastest out of them all, but it's also the only 32bit machine I still run.

Yes I know that technically that a multi channel sata controller running RAID is a poor comparison but its one a lot of people can relate too easily. With ram we still have controllers attached to slots, in dual channel mode it links the controller channels together to act like a single 128bit controller or in the case of a triple channel setup 196bit like the 9** series had. So really simplified its like RAID-0 for RAM.

If you have 4 slots, I'd rather have 4*1GB sticks than a single 4GB DIMM. It's true though its at the point where its hard to tell the differences when you have a large enough pool of memory. One thing where RAM speeds do make a noticeable difference for me is when it comes to video encoding/transcoding. Another where it can provide a noticeable boost is when you have integrated graphics, then it can make a difference, like with that AMD powered Sony.