Bitcoin Forum

 I made my rig as dedicated miner now, its even without monitor, keyboard and mouse. It doesnt need it anymore anyway.  ;D I control it from laptop with Teamviewer. From what I should start? Underclocking mobo really lowers watt consumption in comparison to cool'n'quiet mode cpu @ 800 mhz 1.044v and W7 powersaving mode? Should I underclock\undervolt HT Link as much as possible as the other components? Will I lose mhashes with it?
 Basically, what's the sweet spot with max energy saving and same mhashes?
 Thanks in advance.

You shouldn't lose any hashes.  BTC mining requires negibible bandwidth. We are talking KB per second.

Messing w/ HT link can cause system instabilities though.  You likely will find more power savings turning off junk you don't need.

On my MSI 890FXA-GD70 I have
USB 3.0 - disabled
Secondary LAN - disabled
EIDE controller -disabled
SATA controller - disabled
SATA RAID - disabled
on board sound - disabled
serial port - disabled
monitor LED ( wtf ??? ) - disabled

I have Sempron single core underclocked to 1.6Ghz and undervolted (? can't remember to what).  It likely could go lower but I just tried 1.6GHz and dropped voltage 2 steps and it worked fine.  Never pushed it beyond that.

Oh and the always helpful Power after AC Loss: Always On :)

Since I'm running Semprons I just leave them at 2.8 GHz, drop the voltage to 1.3vcpu and make sure CnQ is enabled. Zero problems on stability and saving 5 watts to more drastically underclock the CPU wasn't worth my time. Maybe if I have 100 of these Semprons I might but not with only 4.

Make sure to power off any monitors when you aren't using them. The 22" I use as a console monitor draws 25w when it is powered on but without input(with an unlit screen).

 So, I did an extreme underclocking.
 CPU is @ 400 mhz now with 1.044v (can't get it lower in bios)! Back to 90s, lol.
 Ram @ 200 mhz and 1.2v (was 667 mhz and 1.5v).
 Bus at 100 mhz (was 200).
 HT Link @ 1000 mhz (was 2000). Can even lower to 400 mhz, but then gpu performance is degrading, both gpus load is lower on 10-15%.
 So far rock stable and same performance.

Did you record a before and after wattage?

I agree that is some extreme underclocking and undervolting.

 I don't have a watt meter yet, but I guess I saved around 50 Wt or more.

At stock clocks, CnQ enabled

Motherboard = Gigabyte 890GPA-UD3H

Athlon II x4 = 1.125v (idle @ 0.84v according to CPUID HWMonitor)
Athlon II x2 = 1.175v
Sempron 140 = 1.05v
Sempron 1200 = 0.95v (using Gigabyte 740G motherboard)

I dont know why the x4 can be undervolted lower than the x2. I'm guessing that the higher clocks and bigger cache of the x2 must be the reason.

So far, these are the lowest voltage that wont BSOD at stock clocks. Tested stable with LTC mining on all cores and also with WCG Clean Energy Project on all cores.

Nice info on voltage! Btw, do you know that you can disable cores as well?

The current bios of my motherboard disabled core unlocking. According to gigabyte's site, I have to go back to an older bios to have the feature enabled again. I'm a bit wary of going back to an older bios, they disabled the feature for a reason and I don't want to tackle any possible problems that maybe introduced by the older bios.

 No, not core unlocking, but to switch off some cores to save energy and possibly undervolt cpu even more. I have Athlon II x4 on my rig and I disabled 2 of its cores, working flawlessly.

Already tried that the time I assembled the rig. Even if I disabled some of the cores (greyed out), no effect with core unlocking disabled. The system will still boot with all cores enabled.

I scrounged up an old Athlon 64 3000+ S939 setup for my mining rig =P
It defaults to 1800mhz @ 1.5vcore
I declocked it to 1ghz @ 1.2vcore and RAM is running lower speed / voltage.
It slowed down my 5970 by a total of like 5mh/s but well worth the power savings of 15-20watts or so.
It has a 2.5" HDD for OS and no other perephials hooked up.
It uses 325watts @ the socket w/ the 5970@ 810/200mhz
Given the PSU isnt even Active PFC, its probably around 75-80% effecient.
Which gives a net power consumption of: 250watts