StingySage: system with lowest possible power consumption?

[Halle]

Hi all,

I have tried out Sage and I love it, and I am about to go ahead and buy a license, but there's just one thing; I installed it for testing on a monstrous old PC that I had lying around unused, but that machine is waaay to power-hungry and noisy to run 24/7. So, I am now spec'ing out a new machine with the following characteristics: can use a PVR-250 for recording (I already have one), has TV-out (ideally on-board but a small low-wattage card would also be OK), and has the lowest-power CPU humanly possible, so I can run it cheap and it'll be easy to cool and keep quiet. I live in Europe and my power bills are high enough to make it worth an initial investment in the hardware in order to save down the road.

I don't really care how physically large the system is -- not looking for ultra-miniaturization. ATX or micro-ATX is fine. I just want really low wattage while still being able to handle recording one standard definition video feed and playing it back. How low can I go? Any suggestions for CPU/mobo combos?

So far I've been looking at AMD Mobile Semprons and the Celeron M, but I don't know if they are even in the running for being powerful enough, or alternately if there aren't even stingier CPUs out there

Thanks very much in advance!

[GTwannabe]

Celerons are a bad idea. Not only do they perform like crap, but most have SpeedStep disabled, so they run at full speed all the time.

An AMD board based on one of the ATI chipsets will be very power efficient with Cool 'n Quiet enabled.

[stanger89]

Of the "major" brands out there, the top contenders are probably AMD and a CnQ system, but also the new Intel Core2 systems with their Enhanced Speedstep.

Either of those options will give you very good performance/power. FWIW, my Athlon X2 system (6600GT) pulls about 100W.

Another option, if you're only doing SD, is to look at an Mini-ITX EPIA system. These are very small, very low powered systems. Though they are/were on the edge performance wise. Though perhaps, if you used an extender (MediaMVP) for playback it might work quite well.

[Oats]

Make sure you choose an effiecent power supply. I would look at Seasonic as most, if not all, of their units have 80% or higher effiecency. They are also very quiet and reliable.

[mdnttoker]

Originally Posted by Oats

Make sure you choose an effiecent power supply. I would look at Seasonic as most, if not all, of their units have 80% or higher effiecency. They are also very quiet and reliable.

I have an AMD x2 system with c&q and an Antec NeoHE PS.

Very happy with it so far...

[Halle]

Thanks for the good advice!

This Athlon 64 3500+ 35w edition looks great to me:

http://www.amdcompare.com/us-en/desk...=ADD3500IAA4CN

Although they don't seem to have such wide availability, and I can't tell if it supports cool'n'quiet or not. On the other hand, maybe at 35w combined with an efficient PSU it doesn't matter too much if it does or it doesn't. I also wonder how much power the PVR-250 draws.

I would pair it with this DFI C51PV-M2/G board due to its onboard TV-out, which ought to let me avoid the extra wattage of a (for this purpose) overpowered video card:

http://www.newegg.com/Product/Produc...82E16813136016

And the Seasonic 330w supply (I think the high PSU efficiency plus the low draw should make 330w more than enough under max usage).

What do you think? Am I on the right track?

[stevech]

I run on an old-ish laptop - pretty low power CPU- throttles up/down speed to save power (the mobile CPUs). Pretty quiet. External USB2 video file drive. Runs with LCD lid closed = no LCD power on. 1GHz Pentium-M, 1GB RAM. Has Svideo out.

[Halle]

Yup, I considered a laptop but it doesn't give me anywhere to attach my PVR-250

[sleepyG]

I think Oats hit the nail on the head regarding what to look for when making an efficient system. You should look at the motherboard and processor combo that draws the least amount of power, but just as important is picking an efficient power supply.
The power ratings for a motherboard and CPU are based on the draw that it pulls from your power supply, that's good to know but that isn't what your power company is going charge you for. Its the draw from the wall socket to your power supply that determines your usage and therefore your system efficiency.
Seasonic does have a reputation for being energy efficient but i'm sure there are other brands just as good out there.

[Halle]

Cool, what a helpful thread, thank you all. So, sleepyG, is this the correct way to reckon the real power usage, for instance if I built a system needing around 100w, with an 88% efficient power supply:

100w / .88 = 113.63w is what the power company will be charging me for

?

BTW, I think I've settled on the following system:

ASUS MN2PV-VM mobo (supports cool'n'quiet)

http://www.newegg.com/Product/Produc...82E16813131014

Athlon 64 3500+ 35w edition

http://www.amdcompare.com/us-en/desk...=ADD3500IAA4CN

I think at 35w it should run cool enough for passive cooling, so it should also be very quiet.

[sleepyG]

Thats a correct calculation and will put you at a ball park figure. The efficiency rating is relative to the output, so if you are drawing 100W the power supply could be 88% efficient but if you draw 75W that efficiency could drop to something like 80%. It all depends on the design of the power supply and what output they are expecting to be used.
A good place to find 80%+ efficient power supplies is www.80plus.org. They do not sell anything, they are "An innovative, electric utility-funded incentive program to integrate more energy-efficient power supplies into desktop computers and servers." If you go to their site and click on "Suppliers" you'll see a list of power supplies that they tested which are over 80% efficient.
This is a real concern when choosing your system. Google takes it as far as to have custom power supplies built to over 90% efficiency. They save a whole lot of money by doing this for their data ceneters Here's an article on it http://computerworld.co.nz/news.nsf/...3?OpenDocument

[stanger89]

SilentPCReview probably has the best data on components (PSUs, CPUs, etc) and their power consumption/efficiency, as well as noise/heat production.

[Halle]

OK, I have ordered components (ended up going in a slightly different and cheaper direction after doing some research at Silentpcreview, but still AMD and c'n'q) and ordered a gadget to read what the draw is at the outlet. I will post back post-build with the outcome, the cost/components, any special configuration I did, and the final wattage under full load. Thanks!

[Goodspike]

I read a review indicating the lastest Intel dual core processors are rather low in power consumption--but it would take you a long time to pay off the price in energy savings. But they might be a nice choice for noise considerations.

I think I recall reading that they were only 65 watts!

[Halle]

True, but the cheapest AMD chips only cost around $45 and use 62 watts, and are still so overpowered for SD TV watching that you can underclock them or run them at a low speed with cool'n'quiet. So there isn't a big upside to paying a premium for Intel. If money was no object (tho it is), I could get an AMD Turion that only uses 25 watts and is still overpowered for SD TV.

[Goodspike]

Originally Posted by Halle

True, but the cheapest AMD chips only cost around $45 and use 62 watts, and are still so overpowered for SD TV watching that you can underclock them or run them at a low speed with cool'n'quiet. So there isn't a big upside to paying a premium for Intel. If money was no object (tho it is), I could get an AMD Turion that only uses 25 watts and is still overpowered for SD TV.

But for HD you need much more. I bought Sage for HD during the time it was beta for HD, so I don't tend to think of SD and Sage. I've never even owned an analog tuner.

[ben_95sl1]

My sempron 3000+ overclocked to ~athlon 3200+ speed (~25%) can do 1080i without any hardware video acceleration (85% cpu), but it can't do 1080i in VMR9 and hardware accel with the 6150 video card...but that has nothing to do with the cpu (it only hovers at 35%). My X2 3800+ with the same motherboard (M2npv-vm) is exactly the same, can't do it smoothly even though 20% cpu. However, overlay is no problem. If you want VMR9 for 1080i, discrete graphics is the way to go.

[Halle]

You guys might enjoy this article:

http://www.silentpcreview.com/article313-page1.html

It's a little bit old but not ridiculously so. Conclusions as I interpret them are that the Core Duo is very powerful and very power efficient (I've got one in my Mac and I sure do love it), other Intel processors aren't particularly energy efficient, and there are multiple AMD processors that are powerful enough for HDTV, as power efficient as a Core Duo, and which range in price from "vastly cheaper than a Core Duo" to "about the same as a Core Duo".

OK, now back to building a SD system based around a PVR-250 with the least possible wattage requirements

[Halle]

Ben, I just looked at your specs and realized that you're using the same mobo that I ordered for this system and a somewhat slower AMD chip (I got a Athlon 64 3500+ because I found one for €62 and they are perfect for undervolting according to SilentPCReview), so I guess my system will also be powerful enough for HDTV if I want to add a discrete card later and another 512MB of RAM, and turn the speed back up again. Neat!

[Halle]

OK, the system is built and functioning. Here's what I got:

AMD Athlon 64 3500+ socket AM2 (Orleans)
Asus M2NPV-VM Socket AM2 motherboard
Seasonic S12 380W PSU
*Akasa EVO Blue Heatsink/Fan for AM2
*Thermaltake Bach HTPC case
512MB Kingston DDR2 PC533 Value RAM
Old 160GB ATA/133 I had lying around
Old PVR-250 card I had lying around
Old DVD burner I had lying around
Old copy of Windows 2000 Professional I had lying around

*One or the other of these was the wrong choice: see below

Total cost of the new parts without VAT: €298.

After assembly, the overall wattage, measured at the outlet, was around 79w, and that was before running the PVR-250 at all. I followed the instructions from SilentPCReview here for using CrystalCPUID:

http://www.silentpcreview.com/article231-page1.html

I opted for that instead of Cool'n'quiet because I wanted to cap the maximum possible CPU rate. This box is really only going to be a SD PVR and server and can get by with a fraction of its maximum power, so there is no reason for it ever to run at 2200mHz.

After a great deal of experimentation with CrystalCPUID, I found the stable voltage and CPU frequency with the most bang for the buck: CPU speed 1800mHz (that is, a multiplier of 9) and voltage of 1.000v. That's 71% of the original voltage giving 81% of the original CPU speed -- good deal! Then, once the heat was so much lower, I was also able to reduce fan speeds and unplug some fans, which lowered the wattage even more.

Final result (so far): system uses 55w (measured at the outlet) when it's showing live tv and recording. The core hovers around 35 celsius and the box is basically silent. I find 35c a little hot and I'm guessing I'll have to reconnect some of the fans in the summer (right now, all that is connected is the fan on the giant EVO heatsink and it is running at lowest speed). However, I think it's acceptable for now and not likely to croak at that heat level.

The CPU shows 20% use under these circumstances. I found a lower speed and multiplier that functions for this chip with CrystalCPUID (6.5x, .875v) but in practical terms it only saves 3 watts and no heat to speak of, and the system starts to wheeze a little bit at 1300mHz, so it doesn't seem to be worth bothering. I wish I could get the wattage lower and I am going to continue to seek other ways to reduce it, although on a practical level, this could be close the bottom limit for a desktop AMD or Intel CPU and a PVR-250/HD/DVD-RW. It's less than my laptop uses I think. I assume a VIA board would do much better -- I strongly considered it but I was worried about the slow CPU and it was too expensive for experimentation.

Pitfalls:

1. The case I chose and the heatsink I chose are not compatible. The heatsink is about 7mm too tall and I can't screw down the top of the case . This is not the end of the world, because I have the whole thing in a little rolling AV shelf so the top is barely visible, but it's nonetheless a pretty stupid outcome. If I was doing it again, I would ditch the case and not the heatsink -- the case fans are very loud for a HTPC case, while the heatsink is pretty much everything you could ask for, down to a potentiometer which goes in one of the back case slots that lets you turn the fan speed up and down manually.

However, it's a close call; other than the lame fans the case is pretty good, and it's hugeness is a major plus when it comes to the near-passive cooling. The inside is pretty well designed, although the machining leaves a little to be desired. It has lots of cute glowing lights on the front that I disconnected because this is StingySage, not ShinySage.

2. For whatever reason, I could not get the AMD cool'n'quiet driver loaded on this machine without crashing it. Could be the RAM I have, or the slot I installed the RAM in, or the weird heatsink which is attached to a non-standard power source, or the revision of my bios firmware, or the phase of the moon. Since it's been my intention to go the CrystalCPUID route since I read about it on SilentPCReview, and that requires turning off the C'N'Q driver, I'm not bothered. But, for someone who wants to run C'N'Q and not CrystalCPUID, there is something slightly off about this setup. It's almost definitely not the mobo or the chip, so I'm leaning towards the heatsink explanation. Could be a mark in favor of keeping the case and changing the heatsink...

Roundup: 55w, 1800mHz, 35 degrees, no perceptible fan or PSU noise (tho some other things in there are still a little noisy). Thank you all for your help!

EDIT: My curiousity wouldn't let me rest about why cool'n'quiet didn't work, so I moved the RAM to another slot and flashed my BIOS with more recent firmware. Afer reboot the cool'n'quiet driver installed without a hitch! I played with it a little bit but its lowest wattage was still a few watts higher than my previous low-wattage record with CrystalCPUID. However, then I went back into CrystalCPUID and the update had made more multipliers and voltages stable, so I found a new lowest possible stable voltage setting, which is a 5x multiplier (1000mHz) at .8v. SageTV playing live tv, recording, and serving over the network only uses 40% CPU at this setting, so it's more than enough, but it shaves a few watts (the system now draws only 50w total while working) and everything runs a couple degrees cooler. Main thing is that if CrystalCPUID makes your head spin, you can get within about 7w of my results just using c'n'q with this setup, as long as you can keep the CPU load low.

Final numbers: 50w, 1000mHz CPU, around 33 degrees at the core, only one low-speed fan running. While installing the c'n'q driver I got to see what the system uses at medium CPU load without any voltage adjustment, which is 80w! I'm glad I didn't spend 2.5x as much for a 35w Athlon 64; I doubt I'd be seeing significantly better results.