Undervolting a Q6600 - Need to save on power consumption - but dont want to lose too much performanc

[DJMK4]

Hi all,

I have inherited a Q6600 CPU and PC bundle for free.

It's to run ESXi and VM's from, however the only thing worrying me about this chip is the power consumption.

I was looking at the idea of lowering the voltage or doing some tweaks to save on power consumption as I dont want it to be costly to run.

However I dont want to lose too much power, whats the best way of achieving this? how much of a performance drop could I expect (%?) and what sort of saving could I see in terms of wattage?

I believe these chips run at 100w+?

 

[DarkBahamut]

I think they have a 95w or 105w TDP depending on the stepping. Undervolting woukd be the best method to reduce power. Given that these usually overclock well on stock volts I would guess there's a decent amount of wriggle room downwards on voltage at stock clocks.

Also make sure you have speedstep/c1e enabled for idle power savings.

 

[DJMK4]

Thanks, I guess I can have speedstep/c1e enabled first for idle power saving, before looking at undervolting and saving more?


The stepping is q6600 slacr G0

I just wanted to see how much performance I would have to sacrifice for a decent saving in power consumption.

I will see if I can see any rough results on the web though when I get a sec.

 

[joeyjojo]

Don't spend too long as the savings probably won't be huge. If you went from 1.325 to 1.1 V (quite a big drop) then that would be maybe a 31% reduction in power consumption = 31 W fully loaded = £35/year.

http://www.tomshardware.co.uk/forum/245475-29-undervolting-q6600

I'd probably start at 1.1 V and test for 100 loops in IBT/24 hours in prime and tweak as necessary. Better not to be at the bleeding edge too if stability is essential.

 

[DJMK4]

Don't spend too long as the savings probably won't be huge. If you went from 1.325 to 1.1 V (quite a big drop) then that would be maybe a 31% reduction in power consumption = 31 W fully loaded = £35/year.

http://www.tomshardware.co.uk/forum/245475-29-undervolting-q6600

I'd probably start at 1.1 V and test for 100 loops in IBT/24 hours in prime and tweak as necessary. Better not to be at the bleeding edge too if stability is essential.

You mean a £35/year saving? Aslong as I can drop it down to about 75-80w maybe I would be happy.

Need to work out average running costs also per month/per year.

 

[Admetos]

All of my machines bar one is undervolted, I even have a couple undervolted and overclocked. Some examples I have an i7 4770k @ 4.2 using just 1.15v and 1600mhz memory down to 1.35 (it's marked 1.5-1.6v), the memory even has timings increased slightly over stock.

My advice is to reduce voltage in small steps until something crashes.

It also helps if you have a PSU putting out more stable power. When I started using Seasonic X PSU's I could undervolt more compared to the OCZ PSU I was using previous.

I have a theory that undervolting is kinder to hardware, as everything is having to deal with less heat. If you have PWM fans due to less heat they will activate less reducing noise.

 

[wazza300]

what board?

not sure if they support negative offset or dvid?

if they do that's the best option to undervolt the cpu provided you can remain stable at stock clocks with lower volts

another option would be to turn off two of the cores? but that would turn it into a dual core performance wise

 

[DJMK4]

Yeah I am not sure what board it is until I get home, the PC was dropped off to me today, I built the rig for my bro a few years ago, all I know is that its a gigabyte board.

Will clarify later on.

Cheers for the tips, my main concern with this rig is that it has the performance I want for now, meaning I dont have to splash out on new hardware (as I tend to stick to laptops these days) but I wanted a rig to rebuild my VM platforms as I got rid of my HP Microserver.

A Q6600 would fit the bill for now as long as I could save on some power consumption

I would rather leave all 4 cores running to be honest but just drop the voltage.

 

[wazza300]

on gigabyte you set cpu v to normal then use a negative - dvid amount,whatever you enter in dvid undervolts the cpu by that amount

 

[drunkenmaster]

You might find, and it depends on the board, that, say for example you have the chip at 3.2Ghz stock(I cant' remember stock speed exactly) and it downclocks to 800Mhz idle, and it's 1.3v stock and at idle it hits 0.9v. If you undervolt you may find that at stock power drops but when it drops to idle it's now at 0.8v and it's no longer stable so crashes under idle, or switching between idle/load.

If it's a machine being used a lot, you may want to disable speedstep and other settings and run consistently at say 3.2Ghz while at 1.1v or whatever setting you find is stable.

If the computer is going to be idle a significant amount you may not save money doing this, so be aware, you may be able to go -.2v at load but at idle only -.05v, and you'd save more money/power with a smaller undervolt but more time at idle.

basically just be aware that less voltage can cause crashes at both ends of the scale.

 

[joeyjojo]

basically just be aware that less voltage can cause crashes at both ends of the scale.

Top tip, but hard to test for. I once tried stability testing in C1E state by limiting Prime in another program to stop the CPU clocking up, but it was tricky.

 

[DJMK4]

Cool thanks for the info guys, will keep this in mind.

By the way the motherboard is a Gigabyte GA-EP35-DS3L

 

[badcompany]

Don't spend too long as the savings probably won't be huge. If you went from 1.325 to 1.1 V (quite a big drop) then that would be maybe a 31% reduction in power consumption = 31 W fully loaded = £35/year.

http://www.tomshardware.co.uk/forum/245475-29-undervolting-q6600

I'd probably start at 1.1 V and test for 100 loops in IBT/24 hours in prime and tweak as necessary. Better not to be at the bleeding edge too if stability is essential.

mine runs 1.1v stock speeds without a hitch