1.5v or 1.35v ram - does it matter?

Just purchased a Thinkpad T430s and will upgrade the memory to 8 or 16 GB.

The weakness of the T430s is the battery life and perhaps heat, due to the small (compared to the T430) enclosure.

Can anyone using 1.35v ram tell me if it really increases battery life and if it runs cooler. The ram slots in the T430s are right next to each other, so cooler running ram would be a plus.

Any suggestions as which ram works well in the T430s (especially 1.35v) would be appreciated.

Thanks

 

At full load, with the memory being taxed, the 1.35V RAM will draw around 2W less power than the 1.5V RAM. When idling you will save around 0.250W with the low voltage RAM

 

Thank you very much.

Do you think the 1.35v ram would improve battery life?

 

I'm sure it will help but probably not by a whole lot if you're expecting hours. Replacing mechanical with a low power SSD will net you better savings but doing both will help more than each indivdually.

 

That seems quite high considering 0.15V @ 2W ~ 13Amps. I'd say difference is fraction of a Watt even at full power. A single stick of laptop RAM likely pulls AT MOST 4W of power, likely much less. I say that because that means at 4W a 1.5V stick would be consuming 2.7Amps, two would be nearly 6 amps. That's a lot of power draw for a stick of RAM.


See this result on desktop RAM where 1.35V vs 1.5V was 1-3W with an error of +/- 0.5 and that's for two sticks of RAM, so even at best 1.5W saved per stick, and that's desktop RAM.

But because I'm such a geek and curious, I am going to test with my two sticks of 1.35v Samsung vs 1.5v G-Skill (both 2x4GB). Why two sticks? Well because my Watt meter is accurate to within 1W, and I doubt it will even show any difference. I may also do with one stick vs two sticks too. But that will have to wait until tomorrow (or so) because it's late, I'm tired, and have to be up at 5am.

 

I'm actually curious to see what you get HTWingNut! Patiently awaiting your results.

 

I'm willing to bet that the power consumption difference is minimal (non-detectable with the kill-a-watt meter).

 

I bought 1.35v ram, and cpu-z said it was running at 1.28v , whether you save battery life i do not know.

John.

 

Its true. Atleast thats what they said in the "An empirical study of performance and power scaling of low voltage DDR3"
I`d love to see it tested out by any members to see if its true though

MacRumors Forums - View Single Post - SSD + 1.35V Ram Power Savings?

 

Good link there. That is pretty impressive actually to save 2W with a 0.15V difference in RAM modules. But 90% of the time the system is idle so the savings is pretty much non-existent. I need to get a more accurate way to measure power draw though within 1W is not very precise.

 

I want to thank everyone for the excellent information.

I am going to install an 8GB (2x4gb) upgrade when my Thinkpad T430s arrives in a couple of weeks,

2 x Kingston 4GB DDR3 1600, Model KTL-TP3C/4G (1.5v)

or

Crucial 8GB Kit (4GBx2), 204-pin SODIMM, DDR3 PC3-12800, CT3291558 (1.3v)

Both are well regarded ram manufactures (as far as I know) and the cost is comparable, so unless anyone knows of a reason to prefer the Kinston modules over the Crucial, I will go with the Crucial.

The Crucial is rated at 1.35v and the Kingston is rated at 1.5v. Although the Crucial 1.35v modules may not make a significant difference in battery life and heat, it may help somewhat and it certainly should not hurt.

Any thoughts would be appreciated.

Thank you.

 

If the cost is about the same, it doesn't hurt to get the lower voltage ones. The IEEE article seems to apply more for servers, where cutting any power consumption for 24/7 operation makes economical sense. Relevant but not as convincing with laptops.

 

All I know is my Samsung 1.35V kicks butt. Not because of it's lower voltage, but because it can overclock like nothing I've seen. It's modest DDR3 1600 CAS11 seems innocent enough until you realize you can clock that sucker to 2133MHz at same timings and even 2400 with slightly looser timings.

 

Yeah Samsung 30nm RAM is known to bee a good overclocker, in desktop chips too.

 

I'm convinced to try the Samsung 1.35v (Samsung MV-3T4G3D/US, kit - 2x4GB). Can anyone confirm that this ram is compatible with the Lenovo Thinkpad T430s. Is the "smaller size" of the sticks an issue?

Thank you.