Power consumption

Vertigo · 1 Apr 2009 at 07:41

I've just thrown together a box to use as a home server. It's nothing special, consisting of an E6300, 4GB of memory, two hard drives, an optical drive and an old 7200 graphics card. The PSU is a Antec 430W.

Now the total energy consumption of the box at idle is around 90W. Is that reasonable or should I be looking at lowering that? Whilst not outrageous, it still seems a bit high to me for an idling machine which doesn't really have that much in it.

semi-pro waster · 1 Apr 2009 at 08:28

The E6300 is rated as up to 65w on it's own, the hard drives will probably each add 5w while idling, say 10-15w for the graphics card, 20-30w for the motherboard (as a very rough guess), 5w per stick of Ram and maybe another 15w for an optical drive idling. I'd say you were pretty much on the money there.

//edit just to note I've rounded up to the nearest 5 in my approximate calculations and perhaps been a bit on the generous side in doing so but I don't think that 90w is exceptional for that sort of system.

Vertigo · 1 Apr 2009 at 09:20

Thanks for that.

Regards the CPU, do these chips still suck the full power rating even when not loaded? Speedstep is only going to drop the clock to 1.6Ghz when idling but would it still suck a proportional amount of power (65W x 6/7 = 56W) even if idling? I thought the rated power consumption was only under full load?

That said, if your estimates are correct then everything else in there is sucking a total of 55-70W so if the total is only 90W that would suggest the CPU is only drawing 20-35W when idling which sounds more reasonable.

As for the graphics card, I'm surprised a crappy card like this one would consume even 10-15W. Shame I can't run it without one at all as it doesn't need it.

pastymuncher · 1 Apr 2009 at 10:05

That seems high to me for a rig with a 7200 in it. My E5200 rig at 3.33Ghz with a 3850 pro only draws 80w at the wall when idling. Ok, the E5200 is more power efficient but the 3850 will draw a lot more than a 7200. When i had a E4300 at 3.2Ghz in there it only drew 85w at idle and that's a 65nm cpu like your E6300.

shadowscotland · 1 Apr 2009 at 10:28

My [email protected]@1.35v/IP35pro/2GB/raptor/8500gt/80plus was around 90w at idle
swaped it to a P5Q and ran it at [email protected] - 75w idle now.

pastymuncher's PSU, CPU and mobo all use less power so even with the 3850 it's lower at idle.

Undervolt the E6300 (if the board can), use a passive cooler and only have the psu fan for cooling.
You could get an earthwatts 380w/new mobo but the payback would be years.

matt_fsr · 1 Apr 2009 at 10:35

Vertigo1 said:
I've just thrown together a box to use as a home server. It's nothing special, consisting of an E6300, 4GB of memory, two hard drives, an optical drive and an old 7200 graphics card. The PSU is a Antec 430W.

Now the total energy consumption of the box at idle is around 90W. Is that reasonable or should I be looking at lowering that? Whilst not outrageous, it still seems a bit high to me for an idling machine which doesn't really have that much in it.

I'd say that sounds fairly accurate, my gaming rig runs around 100W on idle - spec below. The optical drive should pull next to no power unless spinning, but it seems WAY overpowered for a server type machine.

Drop the RAM to 2Gb to save a bit of juice, and if it has onboard gfx use that. Use 1 hard disk if possible.

The cpu wont use the full 65W unless under 100% load - I found speedstep to be utterly worthless in power saving on my machine, so I dont bother with it. Try underclocking and if possible undervolting the CPU a bit, see what you can get it down to.

My media HTPC gets around 50W or so idle, 55-60W during DivX playback - single HDD and stick of RAM, AMD X2 4850e CPU.

semi-pro waster · 1 Apr 2009 at 10:50

Vertigo1 said:
Regards the CPU, do these chips still suck the full power rating even when not loaded? Speedstep is only going to drop the clock to 1.6Ghz when idling but would it still suck a proportional amount of power (65W x 6/7 = 56W) even if idling? I thought the rated power consumption was only under full load?

It shouldn't require full power when not loaded, it can take up to 65w as a maximum. However the total doesn't sound anything to be particularly concerned about, if you were pulling say 150w idling then I might be a bit more worried.

Corasik · 1 Apr 2009 at 11:57

Make sure that speedstep/EIST is enabled too, Even though an E6300 will only drop from 1.83Ghz to 1.6Ghz, it drops the cpu voltage by a couple of 10th's of a volt, and actually saves quite a few watts during idle. I found speedstep has a worthwhile effect on idle power draw.

Reducing the memory from 4gb to 1gb shouldnt affect the server performance much (or 2gb max), and should shave off some watts. Disable any unused ports in bios (com ports, printer ports), same with onboard sound etc.. disable everything thats not in use.

E6300's shouldnt use much more than 25-30 watts idle with speedstep on. (Enable one of the power saving modes in windows XP controll panel if its going to be a windows server (pretty much all except the performance one activate speedstep), linux also has power management options.

Most PSU's lose efficiency at the lowest power draws (relitive to their peak capacity), a 430W supply is probably somewhat overkill, but it's unlikely to be economical to buy a high efficiency 250W supply, and a cheap unbranded supply is unlikely to be power efficient, so most likely its best to stick with the Antec. Problem with power supply efficiency at the extreme's is any power saving made in the hardware can be canceled out by the PSU getting less and less efficient

Vertigo · 1 Apr 2009 at 19:09

Thanks for the replies.

I'll have a play with things and see if I can make a few savings but as long as I'm in the ball park then I don't mind too much. I'm not going to compromise the machine just to say 10-15W, I was more concerned that it should be idling at more like 40-50W and I had something wrong.

I know it's a bit overpowered for a server but it's made up of old used bits that I had lying around or bought on the cheap. Obviously I could replace certain components but it would take forever to recoup the cost through energy savings. Memory is two sticks of 2GB so I could only remove one which is only going to save me a few watts I'd have thought. Need both hard drives for redundancy so that's not an option and, whilst I could potentially undervolt the CPU, I suspect the savings would be minimal and I'd just compromise the performance when the server is called upon to do something processor intensive such as streaming or "RAR"ing.

decto · 1 Apr 2009 at 20:38

You might want to unplug the optical drive when it's not in use... that should save a little and it's not something that is used every day. Only takes a few seconds to connect the power back up when you want to use it...