Thinkpads Forum

I'd like to max out the RAM on my T420 to 16gb. What I'm unclear about is if 10600E (ECC) or 10600R (registered/buffered, probably also ECC) will work, or if I must get non-ECC RAM (as per T420's specs: ).

All the good deals (~$21 per 8gb) are on E and R, apparently pulled from servers. There's suggestion that these won't work in laptops, and I've never seen confirmation that anyone who has 16gb (or at least one 8 stick) in their T420 is using ECC RAM.

(There's also another suggestion that, in servers that are OK with buffered RAM, one shouldn't mix buffered and non-buffered sticks in the same machine. But I'm not even clear that buffered RAM will work at all in the T420.)

Can anyone settle this? Thank you!

Are you looking at SO-DIMMs or regular DIMMs? Laptops take SO-DIMM.

I don't think buffered SO-DIMMs exist and while I'm surprised to find that ECC SO-DIMMs do exist, they're not cheaper than non-ECC SO-DIMMs. I'm not sure whether they'd work, though.

Ah, I'm sure you're right, Sweater Fish Deluxe. These must not have been SO-DIMM's. The 8gb-in-one-stick PC3-10600 (1333MHz) SO-DIMM's are all a lot pricier.

Can I use PC3-12800 (1600MHz) on the T420? I realize it'll run at 1333MHz, but there are way better deals to be had on PC3-12800's. This post suggested it'll work on the T420.

And if so, could I use PC3-12800 DDR3L? This page makes it sound like it might be compatible with systems that support DDR3, but with lower power consumption.

Finally, assuming PC3-12800 DDR3 and PC3-12800 DDR3L both work on the T420, is there any issue with mixing and matching these and/or PC3-10600?

Thank you!

TKuser wrote: ↑

Tue May 16, 2017 4:22 pm

Can I use PC3-12800 (1600MHz) on the T420? I realize it'll run at 1333MHz, but there are way better deals to be had on PC3-12800's. This post suggested it'll work on the T420.

Yep, This will work no problem.

TKuser wrote: ↑

Tue May 16, 2017 4:22 pm

And if so, could I use PC3-12800 DDR3L? This page makes it sound like it might be compatible with systems that support DDR3, but with lower power consumption.

The low power ram is capable of running at both voltages, so it's theoretically functional in pretty much all older machines that use non-L. Where it gets sticky is when you want to install non-L memory in newer machines that expect only low voltage ram.

TKuser wrote: ↑

Tue May 16, 2017 4:22 pm

Finally, assuming PC3-12800 DDR3 and PC3-12800 DDR3L both work on the T420, is there any issue with mixing and matching these and/or PC3-10600?

This will work. The faster module will run at the speed matching the slower one. Generally I would always aim to have a matching pair in there though.

Has anyone in this thread actually have ever had 16Gb running in their T420?

Iirc the T420 chipset does not support 8Gb SO-DIMMS in any configuration.

This has been discussed before.

Brad

My t520 recognizes all 16gb in bios. Cant tell past that cuz dont have an os.

Sent from my E6553 using Tapatalk

Everything I've read is that 16GB is supported by all the Thinkpads from this generation from the X220 to the W520, including T420 and T420s. I haven't tested myself, but many people on these forums reporting it works.

Can I use PC3-12800 (1600MHz) on the T420? I realize it'll run at 1333MHz, but there are way better deals to be had on PC3-12800's.

Early T420 BIOS versions apparently allowed faster RAM to operate at faster speeds than 1333MHz, all the way up to 1866MHz. This was removed for some reason though nobody I've seen has reported problems with it. You might be giving up nice features and fixes by using such an early BIOS and I'm not sure you could notice the difference in speeds. I think some of the custom no-whitelist BIOSes had the RAM speed unlocked as well, but I can't tell which ones.

If you're mixing memory sticks of different speed, they'd operate at the lower speed anyway, though.

Brad wrote: ↑

Tue May 16, 2017 6:41 pm

Has anyone in this thread actually have ever had 16Gb running in their T420?

Iirc the T420 chipset does not support 8Gb SO-DIMMS in any configuration.

This has been discussed before.

Brad

Yup, I run 16GB ram in my 420 and my X220 without any modifications needed.

I am wrong.

I must have been thinking of the T410 not the T420.

I apologize.

Brad

Brad wrote: ↑

Wed May 17, 2017 2:49 am

I am wrong.

I must have been thinking of the T410 not the T420.

I apologize.

Brad

Not at all. Others may have the same impression so it's helpful.

Thank you, Sweater Fish Deluxe and TankPad! Really helpful.

Breathing new life into an old XP machine (fully security patched as discussed elsewhere online): I set out to break the 3.5gb barrier by employing the technique of getting an "unmanaged memory"/PAE-capable RAMDisk tool, and then creating windows paging files on the RAMDisk to greatly increase virtual memory without the big sacrifice in speed that would happen if swapping to disk.

I found three such tools: Gavotte Ramdisk (rramdisk) (free), SuperSpeed Ramdisk (abandoned, new licenses not available for sale), and Primo Ramdisk (commercial, 30-day trial).

Gavotte and SuperSpeed both crashed my machine when attempting to use their PAE modes. Primo did not (and also supports hibernation), and so this technique is seeming viable (only tested with 6gb so far). Will buy one or two 8gb RAM sticks and see how it goes.

This is the RAM I've been rocking in my T420 for the past year: Crucial 16GB Kit (2 X 8GB) 1600 MT/s (PC3L-12800) 204-Pin SODIMM DDR3L Memory (CT2KIT102464BF160B)

The OS detects it as 1600 MHz, but I have not done any benchmarks.

It works great, though.

I'm working with 16GB/1600 for 4 months without issues.

Brad wrote: ↑

Tue May 16, 2017 6:41 pm

Has anyone in this thread actually have ever had 16Gb running in their T420?

Iirc the T420 chipset does not support 8Gb SO-DIMMS in any configuration.

This has been discussed before.

Brad

Reason is yours failed to work is 8 chips per modules. Sandy bridge and Ivy Bridge processors requires 16 chips per module. And yes I do have T420 and HP ultra slim 8200 (sandy bridge) with 16GB using OEM spec modules from ebay using 16 chips. I did try 8 chips at local store and did not work and had to exchange for Corsair Vengeance PC3-12800 16GB kit (DDR3-1600, 16 chips per module). BTW this notebooks I have is using Micron/Crucial , Elpida, Samsung and Hynix. You can order from Crucial or buy any of these I listed on ebay as well.

Haswell processor is the first to use of 1.35V (aka PC3L or DDR3L). Prior to this was 1.5V except mobile Ivy bridge can use 1.35V but desktop only 1.5V. Make sure the memory is capable of dual voltage. Running single purpose 1.35V at 1.5 is risky and hotter. I have no experience with (also mobile Ivy Bridge 16GB x 2 for 32GB) Haswell and later but they can take high density (8 chips per module for 8GB per module, but to run at 16GB per module will use 16 chips).

Cheers, Thinkpadcollection

PC3L-12800s worked fine in my T520 but did not work in my T500. However normal PC3-12800s worked in my T500.

Micron MT16KTF1G64HZ-1G6E1 PC3-12800 1600MHz Laptop Ram Memory DDR3

x2 8gb Sticks of the above Ram working perfectly at 1600mhz here

This is 1.35v / 1.5v compatible Ram btw

IIRC, "EDD RAM" is also called "server RAM" and is designed for use in servers. This because the average server, sitting near sea level, will have 4 memory errors each year from cosmic ray hits. Honest. It gets much worse at altitude.

So, real servers use 9-bit ECC RAM instead of conventional 8-bit RAM. The ninth bit is for the ECC error correction checksum, which allows the server to tell when there is a memory error and do something about it.

9-bit RAM would of course be functionally incompatible in an 8-bit system. You can expect your "not a server" to have four glitches per year at sea level, and scads more if you are using it on an airliner.

The alternative to using ECC memory is to shield the server with some three or four meters of solid rock, or concrete. Although these days, with smaller fabs on the IC's, the problem may require more than that.

Late last year, I had a T420. I never ran it with 16gb but I did have one with 12gb RAM (4gb and 8gb chip in it) and it ran. They don't officially support 8gb chips simply because they weren't around yet when the T420 came out.

Some of the laptops, that are designated as "laptop workstations" and have the optional Xeon CPU's installed, will definitely make use of ECC memory, since the Xeon normally uses ECC and is designed as a workstation (read: server) rather than a desktop.

Presumably, if the T420 had that option, the BIOS would be smart enough to shut out the ninth bit (ECC) if the CPU couldn't use it. Or it might just conclude "memory mismatch" or throw another tantrum.

Either way, I wouldn't throw ECC in a system that wasn't designed for it. Who wants to take a chance on driving a computer insane?

hellosailor wrote: ↑

Thu Jul 13, 2017 3:38 pm

IIRC, "EDD RAM" is also called "server RAM" and is designed for use in servers. This because the average server, sitting near sea level, will have 4 memory errors each year from cosmic ray hits. Honest. It gets much worse at altitude.

So, real servers use 9-bit ECC RAM instead of conventional 8-bit RAM. The ninth bit is for the ECC error correction checksum, which allows the server to tell when there is a memory error and do something about it.

9-bit RAM would of course be functionally incompatible in an 8-bit system. You can expect your "not a server" to have four glitches per year at sea level, and scads more if you are using it on an airliner.

The alternative to using ECC memory is to shield the server with some three or four meters of solid rock, or concrete. Although these days, with smaller fabs on the IC's, the problem may require more than that.

That's when 8 bit memory used to be in 8088/8086 computers, the 9th bit is not ecc, that was parity bit and any error results in a crash with "parity error" displayed.

ECC means Error correcting code means for 64bit memory is group of 8 bit per chip for 8 chips plus one chip of extra 8 bits for ECC and any 1 bit error is now can be corrected, and if more than that results in a reboot with error logged. Some workstation and servers can correct multibit errors and some can disable a bank of memory.

Cheers, thinkpadcollection

thinkpadcollection wrote:

hellosailor wrote: ↑

Thu Jul 13, 2017 3:38 pm

IIRC, "EDD RAM" is also called "server RAM" and is designed for use in servers. This because the average server, sitting near sea level, will have 4 memory errors each year from cosmic ray hits. Honest. It gets much worse at altitude.

So, real servers use 9-bit ECC RAM instead of conventional 8-bit RAM. The ninth bit is for the ECC error correction checksum, which allows the server to tell when there is a memory error and do something about it.

9-bit RAM would of course be functionally incompatible in an 8-bit system. You can expect your "not a server" to have four glitches per year at sea level, and scads more if you are using it on an airliner.

The alternative to using ECC memory is to shield the server with some three or four meters of solid rock, or concrete. Although these days, with smaller fabs on the IC's, the problem may require more than that.

That's when 8 bit memory used to be in 8088/8086 computers, the 9th bit is not ecc, that was parity bit and any error results in a crash with "parity error" displayed.

ECC means Error correcting code means for 64bit memory is group of 8 bit per chip for 8 chips plus one chip of extra 8 bits for ECC and any 1 bit error is now can be corrected, and if more than that results in a reboot with error logged. Some workstation and servers can correct multibit errors and some can disable a bank of memory.

Cheers, thinkpadcollection

Hey, instead of getting cheap ECC memory, we lock the server in a nuclear bomb shelter. Problem solved. Also, I think that would explain why server chips have 9 chips per side instead of 8. You learn something new every day.

"8 chips plus one chip of extra 8 bits "
That would still mean they are using 9 bits instead of 8, adding 8 correction bits to eight, 8-bit sticks.
A difference physically which would probably allow for using one type of stick instead of two, or for turning off the use of the extra correction memory under software control. But without knowing how intelligent the system was about implementing it, the chances of "confusing" the system would still be the same. As would the 8/9 process.

Memory errors may seem trivial to Youtubers, but if that memory error takes a corporate accounting department just "one" significant digit off from the real numbers--that's an expensive problem. Four guaranteed corruptions or guaranteed server crashes every year is a material issue to some users.

Brad wrote: ↑

Tue May 16, 2017 6:41 pm

Has anyone in this thread actually have ever had 16Gb running in their T420?

Iirc the T420 chipset does not support 8Gb SO-DIMMS in any configuration.

This has been discussed before.

Brad

yes it works.
im using 16GB in my T420 and 12GB in my T420S, both working fine and well.

Can second 16GB working too!

Brad wrote: ↑

Tue May 16, 2017 6:41 pm

Has anyone in this thread actually have ever had 16Gb running in their T420?

Iirc the T420 chipset does not support 8Gb SO-DIMMS in any configuration.

This has been discussed before.

Brad

I have two, T420 thinkpads working with 16gb/Ram, (PC3 12800) One, has had 16gb/ram for two years, and still blazing away!

thinkpadcollection wrote: ↑

Fri Jun 23, 2017 11:03 am

Reason is yours failed to work is 8 chips per modules. Sandy bridge and Ivy Bridge processors requires 16 chips per module.

This is not true. I have several SB laptops (T420/T420s/X220) and all work well both with 4 chips per side / 8 chips per module and 8 chips per side / 16 chips per module. All run with 16GB of RAM (2x8GB).

Actually, the less chips in the module, the better, because it's probably RAM manufactured in a newer lithography process and likely to consume less power / run cooler / use tighter timings.

I wanted a dedicated Linux laptop for projects and just picked up a very inexpensive T420s that was in good shape but missing an HD. I immediately upgraded the RAM to 16GB with tow sticks of 8GB PNY MN8GSD31600LV and a 2TB SSD. Everything is working perfectly and no stability issues as far.

I used to have a T61p and really missed that laptop, especially it's keyboard but had to give it up when it couldn't surf the web anymore.

I am very happy so far with the 420s and it seems able to keep up with modern browsers and media at 1080p.