[SOLVED] Can DDR3 1866 MHz SODIMMs work at 1600 MHz?

[MdAyq0l]

I have two pieces of “MTXtec SODIMM DDR3, 204 Pin RAM (8GB DDR3 1866 MHz).” Iternally, the Samsung chips are used.
The laptop for which these two were bought for (with Intel Core i7-3720QM) allows operation at 1866 MHz in case only two memory slots are used, and the speed drops to at most 1600 MHz in case all four memory slots are used. For example, in the current configuration the laptop has 28 GB, composed of

• 4 GB Samsung 1600 MHz,
• 2 × 8 GB MTXtec (as above), and
• 8 GB Kingston 1600 MHz,

and dmidecode reports both 1600 MHz and 1600 Mt/s. BIOS setup shows "Dual Interleave" on its setup page as memory channel mode (which I think is the best “speed” one can have).
My question is: if I buy two more of SODIMMs of the same kind (MTXtec SODIMM DDR3, 204 Pin RAM 8GB DDR3 1866 MHz) and put a total of four into the laptop, will the four still operate at 1600 MHz or will the speed drop even further?

 

[william p]

HWInfo 64 will show what's going on. RAM always has a few lower speed settings included. Should work just fine.
Also the latency timings improve somewhat with the slower speed so you don't lose as much performance as it would seem.
The performance hit from not enough RAM will be much bigger than the small loss to the speed.
That being said-
I would try the 2x8GB 1866 modules and see what happens. 16GB should be more than enough for a laptop and you will have the higher speed also. The chipset may or may not support more than that anyway.

 

[MdAyq0l]

HWInfo 64

Any Linux tool, perhaps?

The chipset may or may not support more than that anyway.

If we believe Dell, 32 GB @ 1600 MHz are supported by the chip. My question is whether the memory would also do it or fallback to a lower setting. As for the latency timings, I have no idea. The laptop already runs fine with 28 = 4+8+8+8 GB (at an unknown frequency). I would like to push it to 32 GB the next time I open it (it will happen within the next few months), but in order to do it, I have to order the right RAM modules in advance.

 

[SamirD]

Any Linux tool, perhaps?

If we believe Dell, 32 GB @ 1600 MHz are supported by the chip. My question is whether the memory would also do it or fallback to a lower setting. As for the latency timings, I have no idea. The laptop already runs fine with 28 = 4+8+8+8 GB (at an unknown frequency). I would like to push it to 32 GB the next time I open it (it will happen within the next few months), but in order to do it, I have to order the right RAM modules in advance.

For linux you can just check your dmesg I believe to see what is detected.

I have an older generation HP workstation that competes with the precision ones and I was able to mix different speeds and sizes of ram without issues so I believe you will be able to do the same. The chipset and processor will adjust the memory timings so you don't have to worry about those.

 

[MdAyq0l]

I edited the question based on more data I have now.

 

[william p]

1866 modules will be able to run at 1600 speed. They will all run at the speed of the slowest module installed. The performance difference will be small. So if you have some 1333 in the mix that's what you will get.

 

[MdAyq0l]

1866 modules will be able to run at 1600 speed. They will all run at the speed of the slowest module installed. The performance difference will be small. So if you have some 1333 in the mix that's what you will get.

Got it. Thanks!!!

 

[SamirD]

I edited the question based on more data I have now.

So I know certain memory controllers/chipsets/cpus will step down on speed when full loaded on ram. I think you're at that point with the 1600 and I don't think putting all 1866mhz would bring you up to 1866, but it is certainly worth a shot if you want to squeeze every drop of performance out of it.

 

[MdAyq0l]

I think you're at that point with the 1600 and I don't think putting all 1866mhz would bring you up to 1866, but it is certainly worth a shot if you want to squeeze every drop of performance out of it.

I also don't think that putting all 1866mhz modules would bring the whole system to work at this speed. I believe Dell on 1600 being the maximum in this case. However, I would be happy if the system together with the full RAM won't step down too much, below 1600.

 

[SamirD]

I also don't think that putting all 1866mhz modules would bring the whole system to work at this speed. I believe Dell on 1600 being the maximum in this case. However, I would be happy if the system together with the full RAM won't step down too much, below 1600.

Sounds like your Dell is similar to my HP and my HP runs at the secondary speed (1333 or 1600--can't remember which). So I think you've got the full speed you're going to get out of it at 1600 even in your current config.

 

[MdAyq0l]

In short, DELL was wrong about its own laptop Precision M6700 (with Intel Core i7-3720QM): a kit of 32 GB RAM now works at 1867 MHz, not at 1600 MHz as they told me. The internal BIOS diagnostics and Memtest86 show no errors. BIOS setup says: “Memory Channel Mode = Dual InterLeave”. The only headache I could imagine now is that the laptop might hypothetically run too hot.

 

[SamirD]

Awesome!

What is the exact model of the Dell so someone can later find your terrific discovery?

I don't think you will run into any temperature issues. An increase in Mhz typically does not increase the heat production. Active use of the memory will though, but that should be within design specs because even 4x 2gb would produce the same heat.

 

[MdAyq0l]

What is the exact model of the Dell so someone can later find your terrific discovery?

Discovery edited .

I don't think you will run into any temperature issues. An increase in Mhz typically does not increase the heat production. Active use of the memory will though, but that should be within design specs because even 4x 2gb would produce the same heat.

Thx! So, does the power consumption remain the same?

 

[SamirD]

Nice! I was wondering why yours could do it and my HP couldn't until I saw that yours is one generation newer processor. Makes perfect sense now. I love the workstation laptops--may weight a ton, but nothing like a 1080p portable working space.