Hi everyone,

I have a Barton 3200+ in a HTPC that I'm trying to passively cool (unsuccessfully). Undervolting/underclocking doesn't seem to reduce the maximum temperatures by enough. I decided that I should try to replace the motherboard/CPU with a low power design.

I had a look at the AMD CPU comparison and it seems that the 35W chips are what I am looking for (ADD3500CNBOX, ADD3800CUBOX, SDD3500CBNOX, SDD3400CBNOX, SDD3200CNBOX, SDD3000CNBOX). However, I believe that all of these have DDR2 controllers whereas I would like something that supports older DDR so that I can reuse my PC3200 memory. Can anyone recommend a low power CPU/motherboard which is greater than or equal to a 3200+ in computational power but supports DDR?

Since you've posted in the Green computing section, it's worth asking whether fanless operation is so important. Buying anything new is, in fact, less ecological than buying nothing at all. The issue is the embodied energy and resources in the new product -- the energy used to extract, manufacture, transport & dispose of a product, and the raw natural materials used. (Someone once cited the scary figure of a couple tons of raw materials need to make one laptop.)

FYI, a CPU cooled fanlessly and one that's cooled with a very quiet fan are audibly indistinguishable in the context of other noise producing components in the PC. Plus it usually runs cooler and more stable and may last longer.

Check http://users.erols.com/chare/elec_pentium.htm#amd : your Barton takes 60W typical 100% load, and 76.8W max. We have a PC in the lab running a similar CPU with 2 quiet 120mm fans at 7V -- one on the big HS, and one in the PSU. This system, under the desk, measures <18 dBA@1m, and is basically inaudible unless you stick you head under the desk next to the thing.

And, on to your main question: Unfortunately, the low power X64s (both the "HTPC edition" that consumes 35W and the "Energy Efficient" version that uses 65W) are only available for the AM2 platform, which is DDR2-only. If you were really excited about it, you could try one of their energy-efficient mobile chips on a MotD motherboard... but that would probably be more expensive than just buying new RAM.

I think Mike hit it on the head- unless you have some compelling reason to go passive, strap a couple of 5v Nexus fans on there and forget it.

I run a socket 754 Sempron 3000+ @1.9Ghz/1.2V; it rarely breaks 30C w/ the stock heatsink & fan @ 5V. The mobo is mATX, allows undervolting and multiplier/frequency change. I would recommend the Biostar Tforce6100 (this comes in 754/939 versions).

Well, I've already gone to a lot of effort to import a HFX classic case from Austria, so it's a compelling reason to me

Sorry if the Green Computing forum is the wrong place to be asking this question - I assumed that people who were interested in such things would know about lowering power requirements. Which forum would you suggest I take my question?

The Vcore on the 3200+ is 1.65V and it becomes unstable below 1.6V. It didnt' seem to make much difference to the peak temperature.

easiest thing would probably be to swap that 3200+ for mobile 2400+ 35W version like i have (see sig). i just checked ebay for "amd athlon 35W" and had two hits. it'll be 35W at stock speeds and you can always undervolt/clock if you need less heat. should be powerful enough for most htpc duties unless you want to mess with a lot of HD content. still not sure you'd be able to go passive at 35W unless you have good case airflow and a decent heatsink. good luck, let us know how it goes.

I *am* planning on using this HTPC for HD. It is the frontend for my MythTV setup and the backend has 4 HD tuners. The 3200+ seems to handle it without any problems.



The case should have no problem dissipating 35W.

At the risk of being in the wrong thread, has anyone spotted the fabled 35W AMD X2 3600+ processors?

I know it is possible to underclock/volt the EE versions, but it seems like the 35W versions just do not exist...

I remember seeing them available shortly after they came out. And I saw one on ebay just recently. Went for about $120-$130. So not a bad price. I only see it included with some barebone kits on ebay now.

how come these 35 watt AM2 processors don't seem to be available anywhere? and if these processors are not available can i undervolt any other AM2 processors to the same level?



"Orleans" (Energy Efficient Small Form Factor, 90 nm)
http://en.wikipedia.org/wiki/List_of_AM ... C_90_nm.29
--
Model Number: Athlon 64 3500+
Frequency: 2200 MHz
L2-Cache: 512 KiB
HyperTransport: 1000 MHz
Multiplier 1: 11x
Voltage: 1.20/1.25 V
TDP: 35 W
Socket: Socket AM2
Release Date: May 23, 2006
Part Number(s): ADD3500IAA4CN
--



"Windsor" (Energy Efficient Small Form Factor, 90 nm)
http://en.wikipedia.org/wiki/List_of_AM ... C_90_nm.29
--
Model Number: Athlon 64 X2 3800+
Frequency: 2000 MHz
L2-Cache: 2 x 512 KiB
HyperTransport: 1000 MHz
Multiplier 1: 10x
Voltage: 1.025/1.075 V
TDP: 35 W
Socket: Socket AM2
Release Date: May 23, 2006
Part Number(s): ADD3800IAA5CU, ADD3800IAT5CU
--

FWIW the 90nm AM2 4200+ 65W TDP part just dropped a more than one third of its price recently. They can be found for about $110 shipped in the US.

That is at 1.25V stock voltage so the TDP should drop nicely when undervolting.

The 90nm AM2 4600+ 65W TDP part dropped a similar amount, has the same stock voltage and can be had for about $130 shipped in the US.

The Brisbane 65nm parts will have lower power draw at idle but there is a noticeable price/performance advantage for the 90nm parts until some point later this year (hopefully very soon) when the 65nm floodgates open wide and the 90nm parts can no long compete on price.

It's also highly significant that most of the 65nm Brisbanes I'm seeing are OEM/Tray parts with no HS/Fan and most of the 90 Windsors are retail parts with a stock HS/Fan included. To me that is worth $10 to $20. Depending on how many spare Heatsinks you have laying around that may not matter to you.

In price order the choices for AM2 socket dual core are:

$80 OEM Brisbane 1.9 3600+ 6x TDP
$110 Retail Windsor 2.2 4200+ 6x TDP

$130 Retail Windsor 2.4 4600+ 6x TDP
$140 Retail Brisbane 2.1 4000+ 6x TDP

I haven't seen any reasonable prices on lower TDP parts (for example I see $400 for a 35W 3800+ but I can't imagine anyone paying that price) and I've made sure not to include prices for any 80+ TDP parts.

I've a 3600+ (90nm, 65w EE) that I managed to get down to 1.05v. The stock voltage for the rare and insanely expensive 3800+ (90nm, 35w EE) is 1.075v.

I have an X2 3600+ Brisbane (65nm) that runs on 0.975v at full speed. It's Prime stable for 1 round. It never topped 32C, using just a stock AMD cooler at 7V, which BTW was a delta fan that sounded like someone cutting through steel. I have the system in an NSK3300 with a Yate Loon D12SL-12 @ 5v on the rear exhaust, and one Nexus 92mm fan on the bottom intake vent. I'm going to put a Nexus 92mm on the stock AMD cooler, as soon as I can figure out how to do it.

Here's some good clues when you read between the lines. 32C ...stock cooler...undervolted fan,under load. You can find FAR more efficient coolers-and you can do swell letting peak temps go 10-15C higher.....meaning loose more fans.

The 65nm process is more watt efficient and cooler. the "performance hit" is too minor to matter unless you are a bleeding edge game guy. The punch a dual core 3600 packs is way beyond a Barton. In fact-a 3000 Sempron probably performs at least as well as the Barton-run WAY cool

You can transfer most socket A stuff,RAM,AGP to a 754 mobo. 754's are vanishing,but get it soon and it's cool. In 754 the 3000 and up Semprons have Cool+Quiet,the 2800 does not. The re are some Venice 754's...just a few more $-you get more cache,but that adds a tiny bit more heat+wattage.

The TDP numbers are sort of misleading There's a big diff in real heat,real watts between the bottom of the line and the top of the line. In a line,the chip rated as a 3600 and the chip rated as 4800 may have the same TDP watts-on paper,yet the reality is the hotter/faster chip never draws that-and the slower/cheaper chip draws way less.

I'm a bit amused at the hype that Core 2's are real cool runners. In real life it does not tend to be so. You can get a cooler quieter rig with the low end X2...and get even cooler/quieter with Semprons.

OK, retail boxed Brisbanes are showing up cheap now.

65W parts (the actual TDP may be lower but they all get lumped in that TDP group)


If you are going to undervolt the Brisbanes are a better option. If you are going to run stock speeds then buy on price between Brisbane and Windsor. Most of the time the Brisbanes will be cheaper from here forward.

The 89W TDP parts go to the 5600 right now and the 6000 is currently only available in a 125w TDP part.

Pulling the trigger on another build this weekend...

65W parts (the actual TDP may be lower but they all get lumped in that TDP group)


There is a 1.9 and a 2.0 GHz version of the 3600+. One has more L2 cache the other has a higher clock speed. The higher clock speed is better for most users but YMMV.

If you are going to undervolt the Brisbanes are a better option. If you are going to run stock speeds then buy on price between Brisbane and Windsor. Most of the time the Brisbanes will be cheaper clock for clock.

The 1.9ghz version is 65nm, the 2.0ghz version is 90nm. Both have the same TDP 65w, but the 65nm version general use alot less power and OC better 2.7ghz-3ghz range.

Can you be more specific?(speed and temp) I've got a 2500 oc'd to 3200 and can't get it under 50c, it's usually more like 53-56c. I Plan on adding a SI-97a
to it soon.

It's a 2500 Barton, not OC'd -- that OC kicks your CPU heat up by the same proportion as the speed increase. There's a Seasonic Super Tornado 300 or 350 directly above the CPU/HS, which is a Thermalright SI-97. A Nexus or Scythe 120 is on the back panel exhaust vent. The fan in the PSU may have been swapped out for a quieter than stock -- can't recall exactly now. The top CD drive bay is open and the cover removed for air inflow; the lower front vent is also nicely open. YOu can feel some airflow at both intake vents.

Typical idle temp is 58C; at load it's gone as high as ~70C, but since the duration is usually very short, we don't worry. The system has been running perfectly stable for years. Probably >2 years in this exact setup, and something like 5 years altogether. Sometimes, when we want to eliminate even this noise in the room but keep the PC on (this is where the fans are tested & recorded) so we end up putting some panels of sound damping directly at the front bezel. This blocks the intake airflow some. We forget to remove it sometimes, & the temp soars up to 70C and higher... till we remember to remove the blocking panels --- even a day or 2 later! No harm ever seems to be done.

If a 5~7V 92mm fan was mounted on the HS, it would probably drop by at least 10C.... but to be honest, I can't be bothered. Why fix it if it ain't broke?

It's not audible at all in a <20 dBA carpeted room unless you stick your head under the table and with 6~12" of the PC.

I have the same thing (2500+ OC'd to 3200+) with a Zalman 7000B-AlCu with a "trimmed" 1500rpm KazeJyu swapped for the fan. These are my idle temps, and note the system temp is roughly 4C higher than ambient right now (it's a warm day in GR).



I don't have my vid card (6600GT AGP) OC'd unless I really need it. And my CPU cooler isn't the greatest in the world (SI-97 would be nice), but I haven't any trouble running these temps, though the CPU varies between 44-45C at idle. I don't have any good load temps, but the CPU never goes above 53C from what I've seen under any real stress. The rest of my setup's in my sig.