I've been experimenting with the speed of my CPU, wanted to see how slow I could run it but still have enough CPU power to do the every day mundane tasks in Windows. (Not gaming)

Why?
To save power and money, make less heat and at the same time maybe extend the life of my PC.

I successfully got it to run as low as 1.2Ghz @0.85 volts, but at that speed there were signs of a slow down, the worst was in media Center where the PC couldn't successfully keep the video playback of HD content running smoothly.

I have ended up with a core speed of 1.6Ghz (roughly) and a core voltage of 0.96V, at this speed the PC seems to run almost as quick as default, not really any noticeable slowdown and HD video playback is perfectly smooth.

I have achieved this underclock by setting the multiplier to 6 instead of 8 (the default) and then reducing the FSB until I got to 1.6Ghz.

Then reducing the CPU voltage to a stable place.

Then reducing the RAM voltage to a stable place also.


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Can you tell what the savings are?

You have a plug in power meter. Could see the overall power savings with that. I bet the graphics being underclocked makes a bigger difference but both would be nice to know.

Good point about the power consumption Snowy, I will post some info about it later.   

My biggest question is how difficult it is to revert, when you decide to fire up a game? Are we talking about loading a profile setting? Or a full-on reboot?

Yes I do have to reboot and make changes in the BIOS when I need to clock it up, doesn't take long with the SSD in there.

The hardest part will be remembering the settings     

You know, as advanced as other components and technologies have become over the years, you would think that you would see similar advancements with the BIOS. But that hasn't changed (other than the settings themselves) in nearly 30 years. My PC Junior from back in the 80's had nearly exactly the same BIOS architecture as we see today.

It's a case of if it aint broken don't fix it.

But with regard to under clocking, have you found out if it's worth the hassle Data ?

I don't think I can be bottomed to do that every time. 

On my PC I have some controls where you can opt for things like performance or eco saving options.  I never use it, I always keep it on performance.

I have some power readings, this took me longer than I thought it would because I have repeated the tests a few times to absolutely make sure the readings are fair and correct.

NOTES:
The power readings are for the entire PC (tower case)

The graphics card (HD4890) is underclocked in both tests to help give a more accurate reading of the CPU power consumption.



Result.

     @ idle = 27watt power saving

     @ Full load (all 4 cores) = 37watt power saving

     Averaging 15c lower temperature


Summing up.

There is a power saving equal to something like 3 to 4 energy saving light bulbs,  its not a huge amount but over a year its going to add up.

The temperature reduction is the most impressive, the CPU runs so cool I could probably remove the heatsink fan and save another watt or two (not recommended).

I'd still like to see the power savings by underclocking the graphics card.
Seeing as this is much easier to do. Not requiring a reboot and all that.

I know, I'm a pain in the 

How much do you pay per kWh ?

Snowy, power consumption savings on the graphics card, new thread.

http://www.datahopa.co.uk/forum/pc-hardware/hd4890-underclocking/


Freddy, there are two prices that I pay, depending on the time of day I think,

Standard = 18.76p.

Reduced =  12.07p

My last electricity bill was £62.30 for a quarter, which I believe is way below the average in the UK and I put that down to all the little power savings I've made around the house, Hmm that could be another topic. 

OK so lets say in the region of 15p/kWh

So that's 0.015 pence per Watt.

idle at 27W and loaded at 37W, so lets say an average of 32W...

32W x 0.015 = 0.48 pence per hour

Say the computer is on 12 hours a day.

That's 12 x 0.48 pence = 5.78 pence per day.

So you're saving about 6p per day.

£0.06 x 365 = £21.90 a year saved.

I think that's right.

Quote from: Data on June 03, 2012, 19:31:51 PM

My last electricity bill was £62.30 for a quarter, which I believe is way below the average in the UK and I put that down to all the little power savings I’ve made around the house, Hmm that could be another topic. 

That's about $31.90USD per month! My computer alone costs that much to run! Our electricity bill runs about 5 times that much for the entire house!

Overclock the beast, and install some solar panels  lol

By the way out of curiosity how much is your wei score affected by under-clocking your rig?

lmao... Solar panels. In England... 

Now if they had some way of power generation that involves rain and gloom...