T3600 UDIMMs

Question

What is the maximum size and speed UDIMM I can use in a T3600 (635w). The manual doesn't have a chart of supported memory configurations. I want to use 4 - 8GB 1600Mhz UDIMMs and have them run at 1600 Mhz. Is that possible?

Thanks!

RoHe · Accepted Answer

Crucial.com is selling kits with 3x8 GB unbuffered RAM for this model, some at 1.35 V and some at 1.5 V. That includes DDR3-1600 so I presume that's an acceptable configuration. Crucial guarantees their RAM will work or they take it back.

RDIMM apparently needs a bigger PSU and won't work with a 425W PSU, according to a note on the Crucial page.

I'll ping my Dell Tech contacts to see if they can help. May take a day or 3 for one of them to respond.

DELL-John C · Accepted Answer

Hi there,

According to the information I have, the Precision T3600 can support DDR3-1600 and DDR3-1333 non-ECC UDIMM memory. There is no mention in our documentation of having a different capacity limit for RDIMMs and UDIMMs so we would take the maximum capacity for UDIMMs to be the same as RDIMMs at 64Gb.

Hope that helps!

gravitypulls · Answer

That's what's confusing.  The configuration tool lets you select UDIMMs when building the system and that's what mine shipped with.  Sometimes memory performance is limited to 1333/1066 when using UDIMMs and the maximum DIMM size can be limited as well.  I don't see any documentation that shows what configurations/speeds are supported.

RoHe · Answer

T3600 -

4 DIMM slots
Memory module capacity: 1 GB, 2 GB, 4 GB, 8 GB, 16 GB
1333 mHz and 1600 mHz DDR3 RDIMM ECC / Non-ECC
Minimum memory: 2 GB
Maximum memory: 64 GB

Manual doesn't mention UDIMM compatibility.

gravitypulls · Answer

Thanks Ron and John, I'm going to give 4, 8GB UDIMMs a try then and I'll let you know if I see any issues.

DELL-John C · Answer

No problem at all! Let us know how you get on!

theflash1932 · Answer

According to the BIOS update release notes, they USED to clock down to 1066/1333 when all four slots were populated, but that was fixed in the latest BIOS (well, 1.4.6 actually, one step back):

* Updated the maximum supported frequency to 1600Mhz for RDIMMs and UDIMMs in both 1
DIMM per channel and 2 DIMMs per channel configurations, when operating at either 1.35V
or 1.5V

http://ftp.dell.com/FOLDER01128937M/1/T320-010500BIOS.txt

The question about DIMM size UDIMM vs. RDIMM is valid, as MOST Dell servers based on similar tech (chipsets, processors) as the T3600 support a max of 2GB UDIMM's, while supporting a max of 8/16/32GB RDIMM's. Most also indicate the effective clock speed is reduced the more DIMM's per channel are used, which has apparently been addressed/updated for this model (probably because there are only 4 slots total).

As to DIMM sizes ... if I were to guess, based on the configurator on the website, I would guess the max size of UDIMM's is 2GB as well, and that RDIMM's are needed for 4GB+ DIMM's and configurations above 8GB total. I realize that not every conceivable configuration can be offered on the website, but this is kind of conspicuous.

These limitations are [pretty] clearly spelled out in the various server manuals. Documentation for the new Precisions is pretty horrible guys (Dell) ... is there a "finished" copy of the manual? Where is the Technical Guide for these?

What processor do you have in here?

It will definitely be interesting to see what you find.

RoHe · Answer

Then why is Crucial selling 3x8 GB kits of unbuffered for this system?

theflash1932 · Answer

Dunno ... maybe it does work - maybe Crucial tested it ... or maybe Crucial is wrong (wouldn't be the first time :)).  All I'm saying is that I know WHY he is asking the question, and we could use a little more documentation.

gravitypulls · Answer

Fired up 4, dual rank 8gb Crucial 1.5v non-ECC UDIMMS with no problems. Running at 1600 Mhz too. Ballistix Sport 8GB if you're wondering. So, there's no problem with 8GB UDIMMs and they'll even run at 1600 Mhz.

Thanks for trying to research this!

RoHe · Answer

:emotion-21:   :emotion-21:

DELL-John C · Answer

Hi gravitypulls,

Thanks for keeping us in the loop! Glad to hear that your new memory is working correctly with your Precision.

If you've any other problems in the future, please don't hesitate to get back in touch!

gravitypulls · Answer

Thanks guys.  Hope they beef the docs up for this workstation soon.  I did notice they released an A08 bios with a bunch of changes/fixes which is a good sign.

isburns · Answer

Looking for a little help on this because I've just tried two different sets of unregistered 4 x 8GB of RAM and cannot achieve the 1600 MHz speed I had before upgrading. I looked all over the T3600 support page and in the manual but can't find any information that describes the limitations of different RAM configurations. Prior to upgrading to 32GB, I had upgraded to unregistered 4 x 4GB that ran at 1600 MHz, so I'm not sure what the problem is. When upgrading to 4 x 8GB, I matched the timings and voltage from the 4 x 4GB set, and when that didn't work I matched the timings from my original configuration (1 x 2GB at 1600Mhz) and that also didn't work.

I'm running the A14 BIOS. Here's what worked and what didn't work:

Runs at 1600 MHz
1 x 2GB unregistered with CL=11, 1.5V (shipped with computer, MT8JTF25664AZ-1G6M1)
4 x 4GB unregistered with CL=9, 1.5V (G.SKILLL F3-12800CL9Q-16GBXL)

Runs at 1333 MHz
4 x 8GB unregistered with CL=9, 1.5V (G.SKILLL F3-1600C9Q-32GXM)
4 x 8GB unregistered with CL=11, 1.5V (CORSAIR CMX32GX3M4A1600C11)

Why won't the 4 x 8GB sets run at 1600 MHz? Note they are all rated to 1600MHz, and are sold in quad channel configuration. I also tried installing only one of the 8GB sticks and the BIOS still reported 1333 MHz.

Any help would be appreciated.

Thanks

Shea

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T3600 UDIMMs

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