Which CPU for low-power system with Abit AN-M2?

lowpowercomputing · Post by **lowpowercomputing** » Sat Aug 16, 2008 8:50 am

Hello,

Update: System's been built. Check this post for results.

I'm looking to replace my Intel D945GCLF. I like the Atom very much but the high power draw of the chipset has created the decision to sell the board/CPU and get something else.

My main concern is to keep power draw as low as possible without much of a hassle. Performance is not that important as that'll be used as a secondary testing/hacking/"playing" system and I found the 1.6GHz Atom with HT to be fast enough most of the time, so about anything should be sufficient.

I have bought an used, but like new Abit AN-M2 from eBay for only â‚¬30 and it looks like a nice board for the price. It should be pretty low-power too. Only downside I could find is that the BIOS doesn't support undervolting but I can do that using software.

My question is: Which CPU to get? I'd like it to be low-power, cool and at least as fast as the Atom 230. My ultimate goal is to reach a lower power consumption than I have now using the D945GCLF.

I've got one of those in mind:

1. Sempron LE.
Pros:
- very cheap.
- undervolts well, low-power.
- runs cool.
- should be fast enough for what I do even when underclocked.
Cons:
- only 256KB L2 in the 11x0 models, 512KB in the 12x0 models. Do those undervolt as much as the 1100?
- Slowest CPUs in AMD's lineup.

2. Sempron X2.
Pros:
- very cheap for a dual-core.
- dual-core, so a bit more power, can be nice in the future.
- can also undervolt well (have seen a report of an X2 2100 going down to 0.7V @ 800MHz and 0.96V @ 1.8GHz).
- should run cool as well but not as cool as the single-core Semprons.
Cons:
- small L2 cache.
- maybe too much for what I need and thus unnecessarily power-hungry?
- mainboard support as those are pretty new. Does anyone know if the AN-M2 supports them with the latest BIOS?

3. Athlon 64-LE.
Pros:
- cheap too for what it is (1MB L2 cache, full range of features).
- a lot of power (was considering the 2.2GHz LE-1600 to undervolt/-clock it).
Cons:
- maybe too much for me?
- power draw too high?

Also, what kind of cooler do you recommend for those? And can anyone tell me how low the AN-M2 can go in terms of Vcore? Seeing that a lot of CPUs can run at 0.8V or even less (not at stock, of course) it would be pretty annoying to find out the board has a lower limit even when using software to undervolt.

Thanks in advance.

edit: One of the inspirations for this is the thread about the Athlon 64 2000+. Seeing those are very hard to get, I'd like to replicate this CPU's results. (So I'm leaning towards an LE-1600.)

QuietOC · Post by **QuietOC** » Sat Aug 16, 2008 7:54 pm

I am currently testing my $50 X2 4400+ at 1.5GHz @ 0.82V (Speedfan reports). I think you could probably pick nearly any AMD CPU, and realize the dual cores will take twice the power of the single cores. I am using CrystalCPUID for doing the undervolting and underclocking.

The X2 errored in ORTHOS pretty fast at 1.6GHz @ 0.82V.

Sorry, I don'y haven't tested the LE-1620 yet, but you should have the best chance with the highest chip like the LE-1640. I think it likely the LE-1600 could run just as cool as the LE-1100.

Highest stable frequencies:
1.5 GHz @ 0.82 V
1.8 GHz @ 0.91 V
2.2 GHz @ 1.01 V

lowpowercomputing · Post by **lowpowercomputing** » Sun Aug 17, 2008 2:56 am

QuietOC, thanks for the response. I've ruled out a dual core as it'll be overkill in that system. I'll also be using CrystalCPUID. So that leaves me with either a Sempron LE or an Athlon 64 LE. Do you think the Athlon would be the better choice in terms of undervoltability and low temperature? The improved performance over the Sempron is certainly something to consider.

Your X2 is a nice chip.

Does anyone have any info on how far the A64LEs can be undervolted? I have no problem with underclocking.

ryboto · Post by **ryboto** » Sun Aug 17, 2008 4:43 am

lowpowercomputing wrote: Your X2 is a nice chip.

Does anyone have any info on how far the A64LEs can be undervolted? I have no problem with underclocking.

I would stick with the Sempron LE's, since they're 65nm, and the only Athlon LE i see on newegg is 90nm. If you want the lowest power/heat, the Sempron LE is probably the best bet.

lowpowercomputing · Post by **lowpowercomputing** » Sun Aug 17, 2008 5:00 am

ryboto, thanks for your comment. I'm watching an LE-1150 on eBay that comes with a Thermaltake TR2R1 which has a 92mm fan. I guess I can still undervolt this thing if it's too loud but does anyone have any comments about that cooler? Cooling an undervolted LE shouldn't be a problem at all.

I was considering the A64LE because of its 1MB L2 and the higher performance compared to a Sempron even at the same clock speed and I thought an undervolted A64 vs. an undervolted Sempron at the same/similar speed should yield a better performance. The Sempron is still cheaper and if I can win that LE-1150 with a cooler it'd be really nice. I'll then probably have a system that is faster than the Atom, quieter, cooler (speaking of the 945GC) and draws less power, not to mention was cheaper to build.

ryboto, I've got one thing to say: Your rig is awesome, especially for the PSU part.

I'm considering using a picoPSU-90 for this system after I find out how much power I need.

ryboto · Post by **ryboto** » Sun Aug 17, 2008 6:26 am

lowpowercomputing wrote: ryboto, I've got one thing to say: Your rig is awesome, especially for the PSU part. I'm considering using a picoPSU-90 for this system after I find out how much power I need.

Thanks! I imagine a PicoPSU-90 should be fine if these are the chips you're considering. I'm actually going to attempt an upgrade to a 45nm Quad core, because based on all the info I can find, my power consumption wont change. When you build this system, be sure to report back on the final build, I'd be really interested in the power draw, those chips sound like they have amazing potential for a low power HTPC.

lowpowercomputing · Post by **lowpowercomputing** » Sun Aug 17, 2008 6:59 am

ryboto wrote:Thanks! I imagine a PicoPSU-90 should be fine if these are the chips you're considering. I'm actually going to attempt an upgrade to a 45nm Quad core, because based on all the info I can find, my power consumption wont change. When you build this system, be sure to report back on the final build, I'd be really interested in the power draw, those chips sound like they have amazing potential for a low power HTPC.

I'll do power consumption tests and if they work out, I'll get the PicoPSU-90, maybe I can even get by with a 60W brick. I'll surely report back once the board and the CPU come in. I'll spring for that LE-1150 with the Thermaltake cooler. For the time being, this system will have a 3.5" HD and a normal 300W ATX PSU though so you may have to wait for better results with a 2.5" HD and a picoPSU.

edit: I'm considering getting a WD800BEVS (WD Scorpio Blue 80GB single platter SATA). Seems like a solid drive.

QuietOC · Post by **QuietOC** » Sun Aug 17, 2008 4:04 pm

ryboto wrote:I would stick with the Sempron LE's, since they're 65nm, and the only Athlon LE i see on newegg is 90nm. If you want the lowest power/heat, the Sempron LE is probably the best bet.

What support do you have for this? The AMD 90nm chips seem to be able to run on less power than their 65nm chips. I think 65nm caused some problem for SOI, which might explain why all their fastest dual-core chips are still 90nm.

ryboto · Post by **ryboto** » Sun Aug 17, 2008 5:21 pm

QuietOC wrote: What support do you have for this? The AMD 90nm chips seem to be able to run on less power than their 65nm chips. I think 65nm caused some problem for SOI, which might explain why all their fastest dual-core chips are still 90nm.

The G2 revision is doing some amazing things in regards to power reduction vs even G1. With G1 I think they had a 2.4ghz 65W part, now AMD can release a 2.9ghz 65W dual core. Maybe the G2 hasnt trickled down to the Sempron LE's though, in that case, I would agree with your assessment.

QuietOC · Post by **QuietOC** » Mon Aug 18, 2008 4:11 am

ryboto wrote:The G2 revision is doing some amazing things in regards to power reduction vs even G1.

Could be, it seems that my $50 X2 4400+ is G2 stepping. I still think the "Orleans" LE-16x0s would be the safest choice.

Newegg currently has a combo deal with an "65W" X2 5000+ and 500GB P7K500 for $113.99 with free shipping. I paid $100.99 for just that hard drive in January.

loimlo · Post by **loimlo** » Mon Aug 18, 2008 4:12 am

Sempron X2 will be G2 revision from 2200+. In other words, Sempron X2 2100+ is still G1 chip. As for 65W G1 part, AMD has had G1 revision 5200+ for a long time, which clocked at 2.7Ghz. It'a an evolution rather than a revolution in terms of clock range for G2 revision.

Frankly speaking, don't bother with idle power draw in such a low-powered system from my experience. I've compared AM2 Athlon64 3000+(90nm), X2 3800+(90nm, though special 35W chip), and BE-2350(65nm G1). At 1G @ 0.8V setting, the difference differed within 5W range with the same system components.

Anyway, anything would be an upgrade given you was satisfied with Atom.

QuietOC · Post by **QuietOC** » Mon Aug 18, 2008 4:22 am

loimlo wrote:At 1G @ 0.8V setting, the difference differed within 5W range with the same system components.

I agree, but that is actually a pretty big difference. I sure many on here would like to know which chip was 5W less. Also, are you testing idle power usage or full load at that setting?

florinp3 · Post by **florinp3** » Mon Aug 18, 2008 6:17 am

I'm curious too, I plan on pairing this board with the lowest power CPU that I can find. Around here I get to choose between Sempron LE-1x00 G1 or G2. I also have "AMD Athlon 64 X2 BE-2300 1.9GHz Brisbane revision G2", but no Sempron X2 2200+.

Is there a power consumption test anywere? - because I can't manage to find one. I'm also interested in single vs. dual-core, the build will be something like NAS + web browser + music-box (anything that my 30/80 MHz Ipod can play

) so I'm not sure if I really need dual-core - it pretty much depends on how big the power difference is. I'm aiming for below Atom power consumption (idle).

QuietOC · Post by **QuietOC** » Mon Aug 18, 2008 7:16 am

florinp3 wrote:I'm curious too, I plan on pairing this board with the lowest power CPU that I can find.

That motherboard looks to have at least a 4 phase VRM circuit, so it will hardly be very efficient. It looks like it is designed for some high wattage quad cores despite the 65W rating. The single DIMM (why bother with 8200 then?) and lack of HDMI and PCIe also make me think this is geared to a different market.

florinp3 · Post by **florinp3** » Mon Aug 18, 2008 7:56 am

Found this (and load) - at idle and with a LE1300 it seems pretty close to Gigabyte's Atom 230, with under-volting/clocking it should go below, am I right?

The Aopen looks great, but I it would be difficult to buy (and too expensive).

martin91 · Post by **martin91** » Mon Aug 18, 2008 8:01 pm

If you don't need the GPU-acceleration of the newest chipset generation (AMD 780G ect.) you should buy the a motherboard with the Nvidia 630a chipset.
The most energy saving boards are the "AsRock AliveNF7G" and the "Abit AN-M2".
The AsRock AliveNF7G supports undervolting in the BIOS, the Abit doesn't. But if you want a system that draws really as less power as possible you can't get around using dynamic clocking&volting tools like CrystalCPUID or RMClock (by the way: rmclock isn't stable with the 65nm amd cpus) under windows or cpupowerd under Linux. As i wrote with the Abit board it's not possible to undervolt in the BIOS, but it has also an advantage concerning undervolting: You can get the new 65nm AM2 cpus below 0,775 Volt if the CPU ist stable at these voltages and the software supports it (there's currently no windows software that supports it really, because only RMClock supports such low voltages, but it's not stable. cpupowerd supports it under linux and is stable). If you choose a voltage under 0,775 V with the AsRock board it supplies 1,5 Volt to the cpu.

You should take a 65nm G2 CPU. Even the X2 3800+ EE SFF with at TDP of 35 W draws undervolted more power than a 65nm G2 also undervolted with a 65 W TDP at the same frequencies. Here's a power consumption test between different AM2 dualcore CPUs.

If you don't use a seperate graphic card and your case isn't tiny it's no problem to run an undervolted X2 65nm G2 AMD cpu completely passive with a Scythe Ninja till 2,4 Ghz, also under full load an even without a fan in your system if you use a picopsu.

I don't think it makes sense to buy a singlecore cpu now because the dualcores are extremely cheap an don't need much more power. It can be more effective to check what your dvd drives and your cardreader needs when these devices are online, but doing nothing (they should do nothing... but they actually do something: draw power, the one devices need more, the others less.)

florinp3 · Post by **florinp3** » Mon Aug 18, 2008 11:55 pm

Thanks martin91 for your help, those links answer my question about power consumption. The only problem remains the motherboard, I want to stick to mini-ITX and that Aopen seems the way to go, but it's kind of expensive.

QuietOC · Post by **QuietOC** » Tue Aug 19, 2008 7:05 am

martin91 wrote:I don't think it makes sense to buy a singlecore cpu now because the dualcores are extremely cheap an don't need much more power.

Dual cores consume at least twice the power of a single core (actually more than double). Fewer cores are always more efficient for the same amount of processing. Multiple cores is as much a dead end as the Pentium 4s hyper-pipeline length.

People forget how long dual processing has been available. There were dual Socket 5 Pentium motherboards. There were even dual 486 systems!

You could argue that mutliple cores makes some sense when the rest of your platform consumes much more energy than your CPU cores. I guess that is the situation with Intel currently.

loimlo · Post by **loimlo** » Tue Aug 19, 2008 7:20 am

3000+ was 43W at idle, BE 2350 was 45W, and X2 3800+ was 47W. I measured power consumption by Seasonic Powerangel.

System components:
Abit NF-M2S
Benq DW800A
WD2500JS
Team 512MB, UMAX 1G DDR2; single channel mode

1x80mm fan with 5V trick
Seasonic SS-300SFD
WinXP SP2

I hope it would help people who interests in this topic. Btw, I don't know the 65nm Sempron64 's power consumption, and I don't want to bother about disassembling my computer anymore for a tiny watt.

QuietOC · Post by **QuietOC** » Tue Aug 19, 2008 7:57 am

loimlo wrote:3000+ was 43W at idle, BE 2350 was 45W, and X2 3800+ was 47W. I measured power consumption by Seasonic Powerangel.

That actually shows that the 65nm process (BE-2350) has less current draw than the 90nm. The platform seems to be consuming around 40W, which is not particularly great. It is too bad the Sempron LE-1250 and LE-1300 cost more than the same clockspeed Athlon X2s.

loimlo · Post by **loimlo** » Tue Aug 19, 2008 10:02 am

How low is low enough? It's hard to say for everyone, and I was hesitant to spend more money on PicoPSU or 2.5' HDD at that time. I got my SS-200SFD/SS-300SFD at a bargain price, about 12$USD each, hence it was hard for me to swallow Pico's price premium. With a better efficiency power, I am sure you can see 35W~40W.

If it were me as a thread initiate to save 10 watts more, I would buy a Pico or 2.5' HD without thinking. You save at least 5W more by going for 2.5' HDD, and 5W more through a better PSU.

lowpowercomputing · Post by **lowpowercomputing** » Fri Aug 22, 2008 7:47 am

To provide a small update to this, I'll pair the Abit AN-M2 with a Sempron LE-1150 (2GHz stock) I got from eBay. The parts haven't arrived yet and I'll post results when I get them and assemble the system.

lowpowercomputing · Post by **lowpowercomputing** » Thu Aug 28, 2008 7:11 am

Another update: I received the components, will be setting up the box soon and then post results. One thing I noticed is that whereas the board is clearly an AN-M2 (it has DVI and no FireWire), AN-M2HD is printed on it. Is this the case for anyone else's AN-M2 as well or a "bug"? I especially bought an AN-M2 so that's no biggie but it still intrigues me.

QuietOC · Post by **QuietOC** » Thu Aug 28, 2008 7:31 am

lowpowercomputing wrote:To provide a small update to this, I'll pair the Abit AN-M2 with a Sempron LE-1150 (2GHz stock) I got from eBay.

I found my "G2" X2 4400+ requires less voltage than the "G2" X2 5000+ to run at the same clockspeeds. It probably is still a great deal of luck of the draw. Why did you go with the LE-1150?

lowpowercomputing · Post by **lowpowercomputing** » Thu Aug 28, 2008 8:51 am

QuietOC wrote:Why did you go with the LE-1150?

I got a good deal on it and the cooler, that one is pretty loud at ~1400RPM (according to the BIOS) though, so I'll look into reducing its speed or omitting it altogether.

My CPU's Vcore is 1.3V according to the BIOS, when the OS is up and running I'll run CPU-Z to check. Wikipedia says the Vcore for those is between 1.2 and 1.35V, so I hope it can be undervolted significantly.

QuietOC · Post by **QuietOC** » Thu Aug 28, 2008 9:21 am

lowpowercomputing wrote: I got a good deal on it and the cooler, that one is pretty loud at ~1400RPM (according to the BIOS) though, so I'll look into reducing its speed or omitting it altogether.

Yes, get CrystalCPUID set the multiplier to 5x (1 GHz) and then voltage to 0.800V. That will probably work fine, but you may be able to get up to 7.5x (1.5 GHz) working at 0.800V. Power increases linearly with clockspeed, so you may be happy with the performance at the lower clockspeed.

I normally have a big heatpipe heatsink on my CPU, so whatever wimpy heatsink you have may require a little extra voltage to remain stable at the increased temperature--especially if you reduce the fan speed or remove the fan.

lowpowercomputing · Post by **lowpowercomputing** » Thu Aug 28, 2008 12:12 pm

Alright, got the system up and running.

Components:

Abit AN-M2 (latest BIOS)
AMD Sempron LE-1150 "G1",1.32V / Thermaltake TR2R1 cooler and the included thermal paste
1GB Kingston ValueRAM DDR2-667 (KVR667D2N5/1G) @ 1.8V
Seagate ST3160022ACE
Fortron 300W ATX PSU

Results (measured by a Voltcraft Energy Check 3000):

Load (2.0GHz @ 1.320V) ---> 64.0 W
Load (2.0GHz @ 0.936V) ---> 46.2 W

Load values taken using Prime95's Torture test, option for maximum heat generation/power consumption. At 2GHz and 0.936V the CPU has been stable for about 10 minutes when I cancelled the test, I've yet to see if it is really stable. How long should Prime95 be run to tell? At 0.912V it failed very quickly.

Using SpeedFan, I was able to find CPU, System, PWM and hard disk temperatures, however, I have entries called Temp1 (similar to the CPU temp) and Core (very low). What are those for?

With the fan at ~1400RPM, CPU temperature maxed out at 38*C at 0.936V. Disconnecting the fan brought it up to 70*C eventually so I cancelled the experiment. It may be the heatsink which is too small or the thermal paste that came with it. It may be a good idea to use Arctic Silver 5 instead.

QuietOC · Post by **QuietOC** » Thu Aug 28, 2008 12:46 pm

lowpowercomputing wrote:Load values taken using Prime95's Torture test, option for maximum heat generation/power consumption. At 2GHz and 0.936V the CPU has been stable for about 10 minutes when I cancelled the test, I've yet to see if it is really stable. How long should Prime95 be run to tell? At 0.912V it failed very quickly.

Sounds normal. Leave it running over night ~8 hours is probably sufficient. It sounds like your Sempron needs less voltage than my "G2" X2 chips. And as you can tell leaving the voltage at the lowest setting and increasing the clockspeed has little effect on power usage.

With the fan at ~1400RPM, CPU temperature maxed out at 38*C at 0.936V. Disconnecting the fan brought it up to 70*C eventually so I cancelled the experiment. It may be the heatsink which is too small or the thermal paste that came with it. It may be a good idea to use Arctic Silver 5 instead.

70*C is actually probably within spec, but a decent heatsink is what you need. Artic Silver is good, but it won't help much (maybe 5 degrees max).

djon · Post by **djon** » Thu Aug 28, 2008 11:38 pm

When you undervolt/underclock with CrystalCPUID or RMClock, is the CPU fixed at the voltage and clock frequency that you define or can you set it to up it's clock frequency while under load?

chrisps · Post by **chrisps** » Thu Aug 28, 2008 11:55 pm

Thanks for the power figures

They are quite interesting. Someone on a German forum ( http://66.102.9.104/translate_c?hl=en&s ... oK31dAhCvg ) managed to get 22W idle with very similar specs, but slightly lower voltages and clock speeds, which suggests to me that PicoPSU could be a good investment if the system is going to idle a lot!