Disabling processor cores, does it makes sense?

[netxzero64]

I have a quad core processor as stated on my sig below, I am thinking to disable at least 2 cores for power saving.. does it makes sense? will it decrease power consumption significantly? if yes, how much wattage will it slash?

or to make it simple, how much wattage will be slashed per core disabled?

your insights will be greatly appreciated thanks! ^^

 

[Arkadrel]

Cool 'N' Quiet™ 2.0 Technology


AMD CoolCore™ Technology - Helps users get more efficient performance by dynamically activating or turning off parts of the processor.



Your CPU already does what you want it too, automatically, to save on power.

Here is a Guide:
http://www.amd.com/us/Documents/Cool_N_Quiet_Installation_Guide3.pdf

 

[nyker96]

I haven't heard x4s has anyway to manually disable 2 cores. but I'd say just let the CNQ do its job.

 

[Seero]

I have a quad core processor as stated on my sig below, I am thinking to disable at least 2 cores for power saving.. does it makes sense? will it decrease power consumption significantly? if yes, how much wattage will it slash?

or to make it simple, how much wattage will be slashed per core disabled?

your insights will be greatly appreciated thanks! ^^

Disabling a core means that particular core won't be used, but that is different from cutting all power towards that core. When the core is not used, the core itself uses very little electricity. What use electricity are parts around the core, and will consume electricity rather or not the core is in use. In short you will not save energy by disabling core. There are several power saving features in bios. Keep them enabled. Keep your case clean as high ambient temp does make the system less efficient.

It is not an advised action, but you can reduce vcore to reduce energy consumption. Such action however require a lot of stability related testing, and the time it takes to do those test probably cost you more than the energy you can save at the end.

 

[LiuKangBakinPie]

Kill John Connor

OP why do you want to save power? Get a better PSU than disabling your cores leave that to windows

 

[veri745]

If you really want to see a benefit of "disabling" cores, you need to wait for Bulldozer or get an i5/i7. They have a feature called power gating which does what you're looking for, and you don't need to configure it except enabling in BIOS

 

[Arkadrel]

Kill John Connor

OP why do you want to save power? Get a better PSU than disabling your cores leave that to windows

Huntkey 700W APFC PSU
Efficiency: 80% efficiency at typical load operation.


Are you suggestion he gets a PSU thats 80-PLUS GOLD certified? so he can have ~90%+ efficiency?

http://www.newegg.com/Product/Produc...-027-_-Product

700watt 90% efficiency. 109$.

Im not sure how much saveing 10% would do (80% vs 90% = 10% gain), or if over says 3 years, it would payback the 109$ price tag.

 

[Maximilian]

If you really want to see a benefit of "disabling" cores, you need to wait for Bulldozer or get an i5/i7. They have a feature called power gating which does what you're looking for, and you don't need to configure it except enabling in BIOS

So if i disabled 3 cores of my i7 920 it wouldnt use 75% less power unless under full load?

 

[LoneNinja]

So if i disabled 3 cores of my i7 920 it wouldnt use 75% less power unless under full load?

Even under full load it wouldn't reduce power by 75% because the cache consumes power too, and your not disabling that.

The L3 cache on K10 causes a good 20W difference under load, ever notice at the same clocks Phenom II consumes noticeably more power than Athlon II? The mobile Phenom II chips don't even have L3, they're technically Athlon II processors, once again to cut power consumption.

I know your talking about I7, but AMD's K10 is the only arch I know of that shows the effect cache has on power consumption.

 

[pm]

Im not sure how much saveing 10% would do (80% vs 90% = 10% gain), or if over says 3 years, it would payback the 109$ price tag.

If you pay around $0.10/kWh, then it's about it's about $1/1W if you run it 24/365. So, if you save 100W that adds up to saving about $100 per year. More if you live in an area with higher electricity (NE USA, California), a bit less if you live in a place with cheaper electricity (central, southern and NW USA).

So if you run your computer 24 hrs/day and 365 days/year at full load (like F@H) and you manage to drop from 300W to 270W by improving your power supply by 10%, then it could pay for itself in 3 years - or less if you live, for example, in the Boston area where rates are twice the national average.

 

[BoomerD]

Huntkey 700W APFC PSU
Efficiency: 80% efficiency at typical load operation.


Are you suggestion he gets a PSU thats 80-PLUS GOLD certified? so he can have ~90%+ efficiency?

http://www.newegg.com/Product/Produc...-027-_-Product

700watt 90% efficiency. 109$.

Im not sure how much saveing 10% would do (80% vs 90% = 10% gain), or if over says 3 years, it would payback the 109$ price tag.

That's hilarious...especially since you linked to a crap (Superflower-based) PSU as a replacement for a mediocre PSU.
At that same price point, he could buy Seasonic, XFX, Antec, or Corsair and have a far more stable and more efficient power supply.


I agree with most...let the BIOS handle the cores.

 

[tweakboy]

No don't do it,, you might gain a bit on TDP

 

[Arkadrel]

@BoomerD

80 PLUS GOLD Certified, was what I searched for on newegg, it was at the top, same wattage as his PSU, looked like it was priced right just going by quick eyeballing.

What makes it a bad PSU? if its efficiency is around 90%?

I understand that youd rather he get a more known brandname, assumeing they have better stability and you might have a point about that. I dont think you can get PSUs much better than 90% effeciency though. Also brandname doesnt always mean better quality/stability of components.

Id have to read lot of reviews of psus where they pick them apart, look at components, and test everything, to be able to answear something like that..... and all I did was just a quick newegg search for "80 plus gold certified". The "idea" of the psu wasnt about brand, it was about him wanting to save power by turning off cores.... and someone suggested he buy a better psu.

And yeah I didnt expect its pricetag to pay itself off within 3years either, from what you might save in electrisity bill.

 

[BoomerD]

@BoomerD

80 PLUS GOLD Certified, was what I searched for on newegg, it was at the top, same wattage as his PSU, looked like it was priced right just going by quick eyeballing.

What makes it a bad PSU? if its efficiency is around 90%?

I understand that youd rather he get a more known brandname, assumeing they have better stability and you might have a point about that. I dont think you can get PSUs much better than 90% effeciency though. Also brandname doesnt always mean better quality/stability of components.

Id have to read lot of reviews of psus where they pick them apart, look at components, and test everything, to be able to answear something like that..... and all I did was just a quick newegg search for "80 plus gold certified". The "idea" of the psu wasnt about brand, it was about him wanting to save power by turning off cores.... and someone suggested he buy a better psu.

And yeah I didnt expect its pricetag to pay itself off within 3years either, from what you might save in electrisity bill.

Unfortunately, "rated efficiency" doesn't always translate into a quality PSU that won't go "POP" and take out your components when it goes.
There are GOOD PSU's and JUNK PSU's all rated as "gold." Why buy "junk" when the same money buys GOOD?

 

[ShadowVVL]

my guess would be a i7 920 runing 2 cores @ 3.2 ghz would probably run at 60-81w at mid to max loads and im not sure about idle.

 

[veri745]

So if i disabled 3 cores of my i7 920 it wouldnt use 75% less power unless under full load?

I don't really understand where you're coming from here, but no, it wouldn't use 75% less power unless you're running it at 100% core usage since unused cores power gate themselves, and also because of cache/NB power usage, like LoneNinja mentioned.

 

[netxzero64]

Regarding the PSU, for the time being I can't do anything about my PSU and i'm not in the position to replace it at the moment or anytime in the future...

I know my PSU just performs +-80% efficiency and that is fine with me..

what I mean on disabling processor cores is through "msconfig" through startup and selection on how many cores to use...

my phenom 2 is old and I don't have the AMD cool core technology... as stated by Arkadrel..