Underclocking AMD X2s

[Phrik]

Looking as to underclocking an X2 3800+ (Manchester, most likely) socket 939. I have no OCing or UCing knowledge. I have researched and still am researching, but I always find more about OCing, and not much useful in on UCing.

I want to lower the amount of power consumption I have on my HTPC/NAS rig, as for now, it sits idle at 100-104W, haven't gotten the chance yet to measure during HD playback.

See HTPC/NAS rig information on my signature.

A little step-by-step on how to underclock or undervolt (or whichever that helps lower down power consumption) will be greatly appreciated.

Thanks a bunch !

 

[Erasmus354]

Take the overclocking advice and instead of raising voltage and clock speed, lower them. Thats all there is to it. Overclocking / Underclocking are the same mechanics, changing the speed. One just makes it faster and the other slower.

 

[Nenu]

Reduce the multiplier, reduce clockspeed, reduce memory divider, reduce voltages.
Test stability.

 

[N_Raged]

My X2 3800+ Manchester is stable at 1.2V and 2400MHz (stock is 1.35V, 2.0GHz), so I actually overclocked and undervolted. I'm still reducing power consumption and heat output.

Without messing with underclocking, you can first try enabling Cool&Quiet which lowers the cpu clock speed when idling. If that's not enough then proceed to UCing.

Before you do anything, familiarize yourself with the 939 platform and the overclocking mindset by looking through this thread:
http://www.hardforum.com/showthread.php?t=888001
Instead of bumping the voltage every time you hit a wall in clock speed. When underclocking you will want to lower the clock speed when you hit a wall when decreasing the voltage. Treat it the exact same as overclocking in terms of checking for stability by running Orthos and the like.

Once you know the limits of your CPU, you may choose to run a certain speed 24/7 or have it change dynamically with the workload on the processor:
http://www.silentpcreview.com/article231-page1.html (just like cool&quiet except more customizable)

More references:
http://www.pcstats.com/articleview.cfm?articleID=1798
http://www.silentpcreview.com/article37-page1.html

 

[Phrik]

My X2 3800+ Manchester is stable at 1.2V and 2400MHz (stock is 1.35V, 2.0GHz), so I actually overclocked and undervolted. I'm still reducing power consumption and heat output.

Without messing with underclocking, you can first try enabling Cool&Quiet which lowers the cpu clock speed when idling. If that's not enough then proceed to UCing.

Before you do anything, familiarize yourself with the 939 platform and the overclocking mindset by looking through this thread:
http://www.hardforum.com/showthread.php?t=888001
Instead of bumping the voltage every time you hit a wall in clock speed. When underclocking you will want to lower the clock speed when you hit a wall when decreasing the voltage. Treat it the exact same as overclocking in terms of checking for stability by running Orthos and the like.

Once you know the limits of your CPU, you may choose to run a certain speed 24/7 or have it change dynamically with the workload on the processor:
http://www.silentpcreview.com/article231-page1.html (just like cool&quiet except more customizable)

More references:
http://www.pcstats.com/articleview.cfm?articleID=1798
http://www.silentpcreview.com/article37-page1.html

I like your setup, under-volting and still over-clocking.... I guess lowering the voltage also lowers power consumption makes sense....

I will read through all those and see what I can do for now, will give it the whole weekend to learn this.

 

[hvrt]

Sorry, a bit off topic. Have my x2 4800+ overclocked and undervolted. 300Mhz increase on 1.28v. Runs at about the same temperature as stock speed and voltage.

 

[Phrik]

My X2 3800+ Manchester is stable at 1.2V and 2400MHz (stock is 1.35V, 2.0GHz), so I actually overclocked and undervolted. I'm still reducing power consumption and heat output.

I did what I could and have learned, I can't even remember anymore what settings I've been mix and matching just to even get it to boot.

Currently my most stable undervolting is at 1.150V for stock frequency, no other. I tried with at least hitting 2200MHz with 1.2V, but it's not stable. The lowest I have tried is 1.10V at 1800MHz (9x), it's not very stable at long high processing, but was way enough for the real world purpose of the box. I'm not sure if I'm missing anything anymore. I've been playing around for 2 weeks now....

Could you maybe with the kindest of your heart let me know every settings you have to get that stable 1.2V at 2.4GHz ? Please ? Please ? Please ?

My testings have been most real world situation to the purpose of this rig, I did simultaneous downloads of 4 GB files from 1 computer, a folder with different files and sizes to another computer, SW firewall on, AV on, encoding with Dr.DivX, and playing a video under MCE. All that running simultaneously for around 30-45 minutes.

I do let it run Prime95 just to see max load stability, just around 30 minutes. It's long stable for 1.1V at 1.8GHz, it's very stable for 1 hour though at 1.125 at 1.8GHz. But then again 1.8GHz ain't much...

Your OC is I think very optimal as to what I would need it for.... 1.2V and 2.4GHz, I think it's as to what I need this rig for... please help me