Precision 7510 : Weird problems with Crucial 16GB RAM ECC stick (Only boots if you mix the RAM!)

Hi,

I have a Dell precision 7510 with a Xeon E3 1535M v5 and 16GB (2x8) ECC RAM (2 Samsung M474A1G43DB0-CPB sticks at 2133Mhz ).

I have recently purchased a 64GB Kit from Crucial of 4x16GB ECC 2400 Mhz (4 sticks like this: http://www.crucial.com/usa/en/ct16g4tfd824a ).

I started by replacing the 2 modules on the back-side but then system doesn't boot. The battery LED that starts blinking suggesting a memory configuration error.

What's funny is that the system boots and works without problem if I leave one of the old Samsung sticks.

2 * 8GB ECC Samsung 2133Mhz = System boots
1 * 8GB ECC Samsung 2133Mhz = System boots
2 * 16GB ECC Crucial 2400Mhz = System don't boots
1 * 16GB ECC Crucial 2400Mhz = System don't boots
1 x 16GB ECC Crucial 2400Mhz + 1 * 8GB ECC Samsung 2133Mhz = System boots!

I tried all possible combinations to discard that any of the sticks is faulty. Its not the case. All sticks are working properly.

There is an identical report about this very same issue here: http://en.community.dell.com/support-forums/laptop/f/3518/t/19681492

I have still no tried to use the RAM behind the keyboard because I may end returning back this memory, so to no waste more time than needed. But according to the report linked above I guess that the system will work with 3 x 16GB ECC Crucial 2400Mhz + 1 * 8GB ECC Samsung 2133Mhz but not with 4 x 16GB ECC Crucial 2400Mhz

I'm running last BIOS version (Version: 1.9.5 Release Date: 12/22/2016)

Has anyone any idea of what is going on or how to fix this?

 

For the record.. when I say that "system boots / doesn't boot" I mean that the system "posts" .. that is the Dell Logo appears on the screen and you are able to access the BIOS.

When the system doesn't boot, you don't see nothing on the screen.. only a LED flashing that indicates a memory configuration error

 

My guess is the ram speed is the issue - when one 2133Mhz stick is installed, can you tell if the other three have downclocked to match speeds?

 

When the system boots with 1x8GB stick at 2133Mhz and 1x16GB at 2400Mhz, both sticks run at at 2133Mhz as expected. The CPU (Xeon E3 1535M v5) is unable to handle memory at more than 2133Mhz, so the 2400Mhz sticks should run down-clocked always.

Maybe the issue is that the BIOS/chipset is not being smart enough to detect that it should down-clock the RAM to match the maximum speed supported by the CPU? And by installing a 2133Mhz it downclocks it to match the speed of the lowest module, therefore matching the one for the CPU?

It can be an explanation for the issue. But if that is the case then this is a serious regression/bug from other systems or expected behaviour.
I have installed RAM faster than what the CPU can handle many many times, and the system always does the right thing: down-clock it to the maximum speed supported by the CPU.

 

Do not know about ECC, but in my pc 64GB NON-ECC 2400 Mhz, works fine

 

I've read reports of stuff like this happening with other systems. This is the difference between supported and unsupported upgrades. Perhaps a different model of 2400Mhz memory works fine, hopefully you can return it.


Sent from my iPhone using Tapatalk

 

Does the SPD data (use CPU-z) for the ECC RAM show a timing for 1066MHz (the base frequency for 2133MHz RAM)?

John

 

Had the same problem. The integrated RAM controller does not *support* 2400 MHz ECC RAM. Though it boots with *some* (old) Crucial DIMMs.

Bought 2x16GB ECC first and then tried to upgrade to 4x16GB ECC. In the meantime the stickers on the (new) Crucial DIMMs had changed and the system did not boot with the new one anymore (though one stick at once was ok).
I called the ProSupport (nice guys ) and they noticed that Dell only supports 2133 MHz ECC RAM in those machines. But we agreed that the old Crucial DIMMs should not boot then either.

I tried all (Samsung, Crucial, Transcend,...) 2400MHz ECC RAMs available -> no luck
The only way to use 64GB ECC RAM in a Dell Precision 7510/7710 are the old Crucial or the 2133MHz DIMMs

side note: I found a similar report about one of the new Lenovo Workstations (P50/P70) some time ago, could not find it anymore - sorry.

Cheers

 

This is the SPD data read with thaiphoon burner for the original RAM module (Samsung 8GB ECC 2133Mhz)




And for the new Crucial 64GB ECC 2400Mhz




As you can see, the Crucial has two entries for ~1067MHz (the base frequency for 2133MHz RAM)

 

One interesting difference I see between the old RAM stick and the new is the DDR4 SPD revision: 1.0 the old one VS 1.1 the new one.

Maybe the Dell BIOS doesn't support DRR4 SPD Revision 1.1 so it is unable to understand the SPD data when there are only SPD 1.1 modules on the system?