Underclock to get lowest power draw

[Deders]

Underclock to get lowest power draw
Hi, I'm trying to underclock my PC for times that I need to leave it on but save on power bills.
I'm using an i5 750 and a MSI P55-GD65

1. So far I've dropped the core amounts from 4 to 2
2. Lowered the Memory to its lowest setting and voltage 754MHz (1.5v)
3. Reduced the BCLK to 125 (it doesn't cold boot from any lower)
4. Dropped the CPU multiplier to 10 so the CPU ranges from (1131-3016) MHz
5. Also dropped the QPI to 4000MHz

• At these settings it is drawing 77W from the wall when idle
• My Stock setting it draws between 80 and 84 from the wall when Idle
• And at my overclocked 3800MHz it draws between 104-105 when Idle

I’m thinking is there anything I can do voltage-wise to lower the idle wattage especially considering there are only 2 cores running. Anyone Tried this before?

 

[Puppies04]

If you have multiple dimms filled with RAM and don't need the memory you could try taking some out and set any unused HDDs to sleep when not in use. Depending on your temps you could also disconnect some case fans, one exhaust should be more than enough with the CPU running at such low usage.

 

[Deders]

If you have multiple dimms filled with RAM and don't need the memory you could try taking some out and set any unused HDDs to sleep when not in use. Depending on your temps you could also disconnect some case fans, one exhaust should be more than enough with the CPU running at such low usage.

Good ideas but I just want to be able to change the profile in the bios without opening the case, also the more you stop and start your hard drives, the quicker they wear out.

I only have 2 dimms as it is. I just want some advice before I start messing with Voltages

I also only have 2 fans, one for the front and one for the back, they are both on controllers. Lowering them saves 1W.

Does anyone think I should try lowering my core voltages by about a third?

Edit: Umm, actually it turns out the BIOS won't let me lower the voltages any lower than standard so case closed I guess

 

[Maximilian]

I dont think undervolting lowers idle power consumption, i remember messing with this on my i5 2400s and it didn't do squat so i just left it at stock.

 

[Idontcare]

Does anyone think I should try lowering my core voltages by about a third?

Edit: Umm, actually it turns out the BIOS won't let me lower the voltages any lower than standard so case closed I guess

Your processor has power-gating, right? So your idle power usage should basically be independent of the voltage. Your loaded power will be dependent though, but you are interested in lower idle power as I understand it.

 

[Puppies04]

I also only have 2 fans, one for the front and one for the back, they are both on controllers. Lowering them saves 1W.

At 77W power draw every watt counts, you either want to save power or you don't.

 

[Deders]

Lol, I was hoping for a little more than that, and there is the danger that I might forget to turn them back up when my CPU is overclocked at full usage.

 

[Puppies04]

Can you tell us what usage scenario you require. There are several ways you could lower your power draw from buying a more efficient PSU to buying a newer CPU. Without knowing what your goals are or why you need to leave the machine idling it is kinda hard to suggest anything more.

 

[KingFatty]

As a fun experiment, does anyone have a kill-a-watt to see what kind of idle power difference we are talking about?

It could turn out that doing 10 jumping jacks inside your house could warm up the house enough to prevent your house heater from having to provide that heat, to offset the power savings here. But I wonder how many jumping jacks it would be. I'm assuming the idle power savings are almost negligible, of course it makes sense to undervolt for big savings when you are not at idle and under load.

 

[Idontcare]

Lol, I was hoping for a little more than that, and there is the danger that I might forget to turn them back up when my CPU is overclocked at full usage.

If you must have your computer on all the time but not allowed to sleep then you might just be better off with a low-power laptop (20-30W) to do whatever you need this idling computer doing and set your OC'ed beast to go to sleep or hibernate.

 

[Deders]

Can you tell us what usage scenario you require. There are several ways you could lower your power draw from buying a more efficient PSU to buying a newer CPU. Without knowing what your goals are or why you need to leave the machine idling it is kinda hard to suggest anything more.

Basically if there are any tasks like defragging or Downloading, Both of which I can instruct he computer to shut down or sleep when finished.

My PSU is a Be-Quiet straight-power 500W (80+gold certified) and my CPU is an i5 750

If you must have your computer on all the time but not allowed to sleep then you might just be better off with a low-power laptop (20-30W) to do whatever you need this idling computer doing and set your OC'ed beast to go to sleep or hibernate.

True but then I'd need to spend 300-800 on a laptop, which wouldn't defrag my computer when it is asleep.

As a fun experiment, does anyone have a kill-a-watt to see what kind of idle power difference we are talking about?

It could turn out that doing 10 jumping jacks inside your house could warm up the house enough to prevent your house heater from having to provide that heat, to offset the power savings here. But I wonder how many jumping jacks it would be. I'm assuming the idle power savings are almost negligible, of course it makes sense to undervolt for big savings when you are not at idle and under load.

My Killawatt figures are in my OP We have an over-energetic dog to help with our heating bills, we find the warmth from his breathing actually makes him a useful part of the house hold. This is mostly his only contribution.

 

[ElFenix]

undervolting my athlon to its lowest stable voltage at 800 mhz yielded something like 15 watts idle power saving per my killawatt (1.2 was default and i got it down to .9 or so, iirc). undervolted my c2q as well. dunno if undervolting a nehalem or later intel processor with proper gating would work as well. haven't tried on my ivy.

 

[KingFatty]

Hmm well if it's one the low side of your numbers, the 3 watt savings would correspond to something more like taking a few deep breaths while seated, not even doing any jumping jacks.

 

[tweakboy]

Use C1E and turbo ,,,, it will drop your CPU speed to 1200 ,,, which is less draw. gl

 

[angevil]

Lowering the voltage for idle saves power, unlike what some say. I have a locked ivy bridge i3, and since i am unable to overclock it, i offset undervolted it by 0,13 volts, and i see it being 1 degrees colder at idle.

I also have a profile for the GPU for when it is idle. It gets more complicated to explain, but the default voltage at stock was 1,15 volts, but the video card can do stock at 1,00 volts. Then i created a profile where i underclocked the core from 790 (stock) to 600, and the memory from 1000 (stock) to 700. Using that profile, if i reduce the voltage from 1,00 by 0,125 the idle GPU temperature drops by 2 degrees.

In summery, undervolting the CPU and GPU by around 0,13 volts lowered for each the idle temperature by 1-2 degrees. I am certain that this represents power savings.

 

[VirtualLarry]

Does the i5-750 even have power gating? I thought that Nehalem did not, not sure about the i5 chips of that generation.