DDR2 power consumption?

valnar · Post by **valnar** » Tue Jan 19, 2010 9:03 am

Does anyone know how many watts various DDR2 RAM modules consume? I have a PC now with a single 2GB v1.8 DDR2 module and want to keep power usage low. What would happen if I added a second module?

Post by **NeilBlanchard** » Tue Jan 19, 2010 9:31 am

Hi,

I don't think that RAM uses very much power. It is less than a hard drive, so if you are getting to the virtual memory much, then adding RAM might lower the power.

The lion's share of the power is used by the CPU, and the video card -- if you are controlling the consumption there, then those savings will swamp any increase from the additional RAM.

valnar · Post by **valnar** » Tue Jan 19, 2010 9:35 am

I'm looking for exact numbers if anyone has any. Maybe one of those online power calculators would break down the memory?

audiojar · Post by **audiojar** » Tue Jan 19, 2010 11:28 am

It's in the milliwatts. No one really bothers to nail down an exact number because it's minimal. And like Neil said, it could likely lower your power consumption by requiring the HD to spin up less.

jessekopelman · Post by **jessekopelman** » Tue Jan 19, 2010 11:32 am

Everything I've read by people who've actually measured says 1-2W per stick of DDR2.

valnar · Post by **valnar** » Tue Jan 19, 2010 11:39 am

jessekopelman wrote:Everything I've read by people who've actually measured says 1-2W per stick of DDR2.

Thanks, that's what I needed to know.

Everyone: Virtual memory is not a problem. It's my firewall box running VMware ESXi with two Unix guests (one BSD, one Linux). And as such, runs 24/7. I already have onboard video and a 2.5" laptop hard drive. Everything else is as low as it can get.

My idle power usage would go from 23w to 25w, so in the scope of things, it's an 8% increase.

lm · Post by lm » Tue Jan 19, 2010 3:40 pm

To put things into perspective, if your machine is on 24/7, then
1W more is a bit less than 9kWh a year.

So when you go to work or grocery store or whatever by bicycle instead of by car even ONCE a year, you already save more than that.

Do it where it counts instead of pointless 1W savings like that.

valnar · Post by **valnar** » Tue Jan 19, 2010 7:00 pm

lm wrote: Do it where it counts instead of pointless 1W savings like that.

You must be in the wrong forum. I'm in SPCR.

We care about the little things here.

audiojar · Post by **audiojar** » Tue Jan 19, 2010 8:39 pm

The point is that you could save much more power in other things in your life but you aren't nit picking about those things. The extra watt in your machine isn't going to affect it's cooling or anything, so the only real affect is on your power bill.

kickaha · Post by **kickaha** » Tue Jan 19, 2010 11:46 pm

Yesterday evening I just added the second ram module to my system.

It was AMD 4850E + Kingston valueram KVR800D2N5/1G on M2AVM-HDMI.
Now it's 2 x KVR800D2N5/1G (in dual channel).

In idle the power consumption difference is negligible, but under strees (2 memtest) I've seen it increase by about 3W.

Kingston states (http://www.valueram.com/datasheets/KVR800D2N5_1G.pdf) that this ram uses 1.355W on load, so I guess there is also a little increase in cpu/motherboard consumption.