Thinkpads Forum

Does anyone know if an increase in memory will draw more power from the battery? Will a 512 mb draw more than a 256 mb? Will 2 sticks draw more than 1? If so, is there any info on how much.

i know very little about electronics, electrical engineering, computers, and computer technology. However, I would quite easily bet quite a lot that the answer to your first three questions is No. Also, even if the answer turns out to be Yes, I would quite easily bet quite a lot that any additional power used by any additional ram memory is far less than any additional power used to access the hard drive or virtual memory in the absence of needed ram. in my ignorance, i bet that there is no practical reason to worry about additional power needed to use additional memory, unless such memory usage and power consumption is going to lead you to run different kinds of software - and i've never heard of such a thing.

Technically yes. Practically no. And here's proof:

When you put your Tpad on standby, the only thing (besides some wake-up circuitry) that should remain powered is your memory. I have 1GB in mine, and it drains less than 1% of the battery per hour. If you assume power consumption vs. amount of RAM to be linear, then an additional 512 MB of RAM would technically drain your battery less than 1% over 2 hours and less than 2% over 4 hours.

Four hours is bordering on your maximum battery life. Therefore, in the time it takes you to run down your entire battery, that extra 512 MB of RAM would cost you less than 2%, leaving 98% of the consumption for the other major power hogs
- processor (cpu, graphics)
- fan
- display
- hdd
- wireless
- cdrom

The numbers I used are probably conservative. If I had to bet, the RAM power consumption is actually less than that.

Now that I think about this, what I said was probably a gross oversimplification. It probably depends a the RAM technology and how much of it is being actively accessed - although I believe the RAM these days is dynamic, meaning all of the RAM gets refreshed whether it is used or not.

Anyways, if I had to guess, I would still say that the power consumption due to the RAM would be very very small. Somebody could do a benchmark, but the power consumption due to the RAM would probably be overshadowed by other variables.

Actually having as much RAM as possible can increase your battery life.

More RAM usually means less usage of Virtual Memory and therefore less HDD action, which is is very power consuming.

I'd like to add my 2cents...

Yes, an additional memory module will require some power.
And what the others already said: The reduction of HDD-activity cause by the additional memory may cause an increased time on batteries. This won't be true if you just switch on the notebook and don't touch it until it's empty because this would be not memory limited.
Nevertheless I'd not expect any big differences in battery life.