New Machine - Want Best Efficiency (i.e. Fast but Low-Power). Which way to go?

[Fun Guy]

I've been out of the game for a while and I certainly found out how long once I tried to figure out WTH was going on with all these different processors out now.

Basically I'm constructing a power rig that will have a 30" display in the center with two 20" displays turned portrait, one on either side of the 30" display (2560x1600 center with 1200x1600 on either side). This machine will do everything from video editing to heavy statistical modeling, and perhaps a game or two as well.

I'd like this rig to be power-efficient. I've noticed that some of the Socket 1366 processors meant for dual-CPU rigs have 'L's in front of them and 40w-60w operating power (i.e. the Xeon L5520, L5530, L5630, L5640). This is pretty damn appealing to me from a power/heat/efficiency perspective. I will also get two air-cooled PCI Express 2.0 x16 video cards for the same reason.

So my questions are...

(1) How are these low-power processors able to operate this low in comparison to their higher-power cousins/brothers? What is sacrificed, if anything?

(2) I've noticed that the processors meant for single processor boards do not have L-designations. Can I use one of the low-power processors (e.g. the L5640 = 2.40Ghz, 12MB L3, 1066Mhz mem speed, 6-cores, 12-threads, 60W) in a single-processor board anyway?

(3) Is there any extra overhead in managing a dual-processor board than a single? Reason being, if I can't put one of those low-power processors in a single processor board, I would be tempted to go dual-CPU.

If I'm missing anything, please let me know...like I said, I've been out of it for so long I have NO IDEA what is going on in the CPU world, nor do I have 2 weeks to get up to speed.

Thanks!!

 

[Mr. Pedantic]

Why is power efficiency so important? And is idle efficiency more important or load efficiency? I would think that for your workload, power would be much more important than efficiency. Besides, the Nehalems, especially the Lynnfield ones, are pretty good with power usage anyway.

1) They're probably cherry-picked for low-voltage operation. Which means that just like how normal cherry-picking gives you a set of processors that can clock higher, you get a set of procs that can run at lower voltage before BSODing. Most normal chips at that speed bin should also be able to run at low voltages as well (undervolting is probably the first thing you should do to get better efficiency), it's just that the low-voltage ones might go a bit lower.

2) Yes.

 

[khon]

You could go for the low power options, but honestly it would end up costing you not just time, but also ironically increased electricity consumption.

The thing is the low power versions do use less electricity, but they're also significantly slower. By themselves they're still able to get more done with the same amount of electricity than the higher power parts, but when you factor in all the other components in your computer, you actually end up using more electricity with the low power CPUs.

For an example of what I'm talking about have a look at this comparison between Intel Atom and Intel i3-530: http://www.tomshardware.com/reviews/d510mo-intel-atom,2616.html

Basically imagine you have a CPU that can do 80% of the work, but only uses 60% of the power. That sounds great right ? Well not so much once you add in the rest of the computer.

Fictional example:
System #1. (100% speed)
CPU - 100W
Rest of the computer - 200W
Time for calculation - 1 hour
Total power used: 300Wh

System #2. (80% speed)
CPU - 60W
Rest of the computer - 200W
Time for calculation - 1.25 hours
Total power used - 325Wh

As such I'd go for the fastest processor I could find if I was you. The only way the low power parts make sense is if you're not doing cpu intensive work, and you're going to be doing video editing and statistical modelling, which is about as cpu intensive a workload as you're likely to find.

 

[Spook]

My X6 is a power hog using all 6Cores, 140w or so, then OC even more, but I don't allways need the 6 cores, so, I have setup 2x profiles in my Bios, one for 6x3.8Ghz, and one for 2x3.5Ghz... The 3.5Ghz is more than enough for most of my functions, but when I need to transcode or want to play a few select games, I fire up the 6x3.8ghz... just an Idea, it will lower your power consumption on one hand, but give you the option of having the higher power on the other.

Same can be done with the i7's too... you can shutoff HT, and/or a just run on a couple cores instead of all 4...

 

[CurseTheSky]

This machine will do everything from video editing to heavy statistical modeling, and perhaps a game or two as well.

Figure out how many cores / threads the programs you'll be running scale to (2 cores, 4 cores, 8 cores, etc.) and then you'll have your answer. As others mentioned, you'd be better off burning up the power during a shorter full-load than spending more time during full-load, albeit at a lower total power consumption. That is, unless you're planning on having this thing crunch numbers 24/7.

 

[Fun Guy]

My X6 is a power hog using all 6Cores, 140w or so, then OC even more, but I don't allways need the 6 cores, so, I have setup 2x profiles in my Bios, one for 6x3.8Ghz, and one for 2x3.5Ghz... The 3.5Ghz is more than enough for most of my functions, but when I need to transcode or want to play a few select games, I fire up the 6x3.8ghz... just an Idea, it will lower your power consumption on one hand, but give you the option of having the higher power on the other.

Same can be done with the i7's too... you can shutoff HT, and/or a just run on a couple cores instead of all 4...

Very, very interesting....thanks for the idea!!

How do you like the 6-core processor - does it work as advertised? Can you/do you see an material increase in power over let's say, a 4-core CPU?

 

[Spook]

Im running a 2x I7-860 OC to 3.4Ghz, and I have my AMD x6 OC to 3.8Ghz, and I would say they are comparable in power/time to encode, but I haven't actually encoded the same movie with both to see which is faster, I probably should, just to test. In the end, I use all 3 systems to encode, depending how much video I have.

I'll Run a 1080P encode on the same video and see what I get.

 

[aigomorla]

Basically I'm constructing a power rig that will have a 30" display in the center with two 20" displays turned portrait, one on either side of the 30" display (2560x1600 center with 1200x1600 on either side). This machine will do everything from video editing to heavy statistical modeling, and perhaps a game or two as well.

I'd like this rig to be power-efficient. I've noticed that some of the Socket 1366 processors meant for dual-CPU rigs have 'L's in front of them and 40w-60w operating power (i.e. the Xeon L5520, L5530, L5630, L5640). This is pretty damn appealing to me from a power/heat/efficiency perspective. I will also get two air-cooled PCI Express 2.0 x16 video cards for the same reason.

im sorry.. intel + render box =! power efficient.

And it completely depends on your objective.

Second if this is a mission critical machine, on the heavy statisical modeling.. then MAKE A NEW MACHINE FOR THAT.

DONT EVER MIX YOUR WORK AND GAMING MACHINE TOGETHER.

Work machine.. you should never Overclock.. your after stability and endurance.

Gaming machine... *you make this your toy... and mickey mouse this.. not the work machine.*


Also, as others have said... theres a ton of difference between a machine who spends most of there time in IDLE.. vs one thats constantly on load.

Very, very interesting....thanks for the idea!!

How do you like the 6-core processor - does it work as advertised? Can you/do you see an material increase in power over let's say, a 4-core CPU?

Once again its completely dependant on your work and how the program takes multi cores.
And you cant really cross compare an intel i7 platform with a PH X6 platform, because the i7 has HT.

In some applications, the HT actually boosts your performance by 33%. (encoding)
But in other applications the HT can kill your performance by 33% (linX Flop calculation with HT on)

I'll Run a 1080P encode on the same video and see what I get.

i7's dominate encoding period.
There is no competition.