I have been hoping to replace my 0 fan sempron 3000+ system so am looking for something cheap and able to go fanless, with a less than rediculous heatsink (read: orochi).

I have seen 0 fan C2D systems, and core iX if underclocked... but what about the AMD side??

Putting upgrade paths (and atom) aside, is an AMD platform preffered for a 0 fan/cheap/DDR3 scenario? (compared to G41 i guess?)

I've got a fanless AMD with a dinky heatsink but it's factory-underclocked so it's not much better than a fast dual-core Atom except for the features (virtualization extension, ECC support, graphics and so on).
My part is not availably for a reasonable price to the general public (I bought it as part of a full system) but AMD has recently released nice Atom competitors to the public. You might be interested in those if you don't want a big upgrade.

It's unclear how you managed to get your old CPU to work without a fan because there are many Sempron 3000+ models. If you've got the 35W part there are not many mainstream CPUs which consume that little power (aside from the mobile parts of course). Obviously the modern mainstream AMD CPU are much faster than yours and have the potential to waste less power. AMD has released 25W dual-cores with a regular socket to OEMs about 18 months ago for instance. Dell used them for instance. They're underclocked and quite slow compared to mainstream modern CPUs but would still be a serious upgrade for you.
So unless you can source an OEM part you want to pay for mobile parts it comes down to manual underclocking I guess... how well is it supported by particular boards and CPU I don't know. There are 45W quad-cores but that's probably too much and I don't know if they'd be any better than regular parts if you're going to underclock anyway.

Sempron 140 or 145 are a single core version of the Athlon X2. The 140 is specified as 45W TDP, but with a good motherboard & bios it can be undervolted to ridiculous extents. I have one with an ASUS board (generally good undervolt options) I picked up for ~$95 US, and it works great for my MythTV frontend.

TBH, though, if I were buying now, and if price was no object, I would probably go with a lower power Sandy Bridge. (i3-2100T is stock 35W TDP and would run circles around the sempron, but at 3x-4x the cost). And I am a big AMD fan

I am personally not buying anything until I see what Bulldozer/Llano offer.

I wouldn't bother with a Sempron. Get at least a dual-core. The slow ones can be cooled passively better than any desktop Sempron or Intel (bar Atoms). If you don't mind slow and don't have a board, get a Zacate board (they come with a CPU). The dual-core Regors are faster of course but even the slowest desktop Regors are going to consume a bit more.

The sempron 140 is the same die as an Athlon II (245 I believe), but with one core disabled. So anything you could do (in terms of cooling) with the dual core version can be done more easily with it

I actually unlocked the second core on the one I bought, and it seemed perfectly stable, but I disabled it because it increased power consumptions by 5W/15W idle/load DC (and one core was plenty)

There are dual-cores which are factory-underclocked and they consume less than that Sempron. The Sempron is going to be faster at single-threaded tasks but overall the dual-core will perform better and require less cooling.
And unless you need good single-threaded performance, a Zacate would not perform too badly compared to that Sempron and consume even less.
But if you already have a board that can underclock/undervolt that Sempron, its price would make it very attractive obviously. No doubt its power consumption could drop quite low if you could tweak it.

Like andymcca pointed out, the Sempron 140 is just a normal Athlon II X2 with the second core disabled. It's dirt cheap (or was when I got mine anyway) and you've got a chance of unlocking the second core.
A factory-underclocked dual core proper will be more expensive. So it all depends on if one really need that second core, if one can be bothered to underclock manually and how much money one like to spend.

I also would like to point out that while it's possible to cool things passively, if you can add just one slow 120mm case fan, spinning at 500-600 RPM or something you can cool a really quite powerful system. I'm pointing it out since the Sempron 3000+ system mb2 is using now actually had one fan according to the link in his signature. And with a mechanical HDD the system already has moving parts..

mb2, how much CPU power do you need? For my disk server a while back I went from my underclocked Sempron 140 system (38W AC idle, one HDD spinning) to a less power hungry Atom system (D945GSEJT) but now I'm going Sandy Bridge because the Atom N270 is painfully slow..

Nice to see some interest in this topic.

HFat; mine is a Palermo Sempron (desktop/s754/90nm). It is quite funny really because at the time the 2600+/2800+ which didn't have CnQ (or a mobile CPU) could accept lower voltages.. and this still maxes ~60*C at full load. I should probably buy a 2800/2600+ just to see how much lower it goes considering how rediculously cheap they can be had today.

Vicotnik; well done for doing your homework, but that post is 5 years old, when I didn't have the freezer 7 or pico psu. I didn't think anyone would care about such old hardware so i didn't update it. But i have now for you!
I have an enclosed HDD but can definitely see an upgrade to an SSD coming well within the life of the next one.

As my sig, this isn't my main PC, I just use it for work.. so its not really that the old one is much too slow. The main issue is there is no graphics driver for the IGP for windows 7.. and with prices of DDR3 and some motherboards so low, why not upgrade.. more speed is never a bad thing!

The sempron 140 (/150) is what i thought would be an obvious no-brainer. 45nm and only a few hundred mhz more than my 5-year old sempy. By all logic it should run fanless on a stock HS. Yet I haven't seen any fanless setups on here (this post was hoping to find some), and in one build I saw was pulling >100W load with 1 HDD. (for reference, mine was around 70-5w on an ATX PSU). This makes me think that, being of dual-core origin, the 140 perhaps has more leakage because of this...
Thanks for the data on the power used enabling the 2nd core, andymcca. +15W on a CPU seems like it could easily tip a 0 fan system over the edge... do you have a write up post for your system?.. Do you undervolt?.. i would be really interested to know how low you would have to go on the CPU speed to get fanless, if it won't do it at stock speed.

I can't get a zacate board for cheap enough to make it worthwhile really. Besides would it really be an upgrade?
The real attraction of a 140 is that I could possibly get a AM3+ board soon and then have an upgrade path to 32nm/lower.

If your current fanless system draws 60W at load then you should be able to cool a modern system the same way, if it draws less. My Sempron 140 system was 38W idle, I regret that I didn't do any full load tests.. But I'm sure it wouldn't pull more than 60W at load. Here is more info about that system.

Zacate was a bit disappointing imo. If you want to go AMD perhaps it's better to wait a little while, more interesting things are coming I'm sure. I also like AMD but Intel is looking very sweet right now..

I wonder what you guys are running that makes you discount dual-cores. Sure, fileservers don't need dual-cores but even Atoms are overkill for fileservers.
Obviously a dual-core Zacate would be an upgrade over an old Sempron 3000+ unless you don't use the second core. There are cheap Zacates available now but it's kind of a moot point if you already have gear capable of cooling more powerful CPUs you're planning to reuse.

If you can run a CPU rated at 62W (I know the actual power consumption is lower) without any fans, you should be able to run a slow 45nm dual-core. If your board can underclock and undervolt, you won't have to buy a 45W part and it would not cost much more than a Sempron because you can underclock aggressively if you're only trying to beat a Sempron (in most cases... I don't know what you're trying to run on that CPU).

Most logical thing to me is clear. Wait for Llano 32nm chips. Should blow anything else out of the water in terms of making it easy to be fanless on amd side.

Who's discounting dual cores? They are sometimes not needed, as you say yourself. Depends on the requirements and it's difficult to recommend specific stuff unless those are specified.

I have an Athlon II X2 250u (25W TDP dual-core K10 at 1.6 GHz). The chip runs at 1.050V VID at 1.6 GHz and at 0.900V VID at 800 MHz. But it can undervolt to 0.9V / 0.75V if desired. Combined with 4 GB ECC RAM, AMD 760G mini-ATX, picoPSU-160XT and a newest Seasonic AC-DC adapter, I get just 23W at idle and approximately 45W at load. I cool it with Scythe Big Shuriken without fan. The CPU temperature gets to ~70 degrees with Prime95 but since this is a very low voltage CPU, it can handle that temperature without issues (it is designed for Tcasemax of 81 degrees). And it runs Prime95 x64 for 10 days without error.

It might be possible to get Athlon II X2 270u 25W 2 GHz dual-core if you are lucky.


I was thinking this will be the case but then realized it probably won't due to:
1) Llano does not support ECC memory.
2) Llano is a mass market product. I expect it won't be a low voltage device. I will for sure have an option for undervolting but at stock, it probably will have higher power consumption than Athlon II 2XXu.

As the processor gets hotter it will needlessly draw additional power. It only makes sense to build such a system if you could limit the load of the processor. 25W is still quite a lot, especially for smaller cases.

Nothing has changed in this business. The cooler, the better. Complete fanless would only make reasonable sense for really low-powered devices. Such as your Android gadget for example.

I wonder how hot this summer is going to get

Currently I am running a Phenom II 555 BE, which is an 80W TDP, 3.2 HGz, 2-core part. On the Asus 890G board, I unlocked the other 2 cores so all 4 cores are now running at 3.2 GHz. 4GB RAM, 1 WD 2TB Green, powered by Seasonic X400. The CPU heatsink is a Noctua 14cm downblower -- with the fan set so it only turns on when CPU exceeds 60C. There are no other fans -- but the components are simply laid out on a wooden board, w/o any enclosure, it just fits in the ~7" high shelf of my TV stand. It is being used as a HTPC -- overkill, but it's super smooth with any kind of HD file playback, virtually ignores the challenges of bad encodes.

Idle power is ~40W, typical HD playback is 50~55W, max I have seen on the AC meter is a touch over 60W. PSU is permanently plugged into AC meter. CPU temp is always <50C, and the heatsink fan NEVER has turned on in actual operation.

I'd say this thing is running fanless. Good fanless functionality is not limited or defined by TDP, per se, it's more about how the machine is used. Checking what happens w/ a fanless system running Prime95 & Furmark is all good and fine, but most PCs don't need to pass anything that strenuous to be perfectly usable. My system would pass it because that heatsink/fan can cool the CPU w/o any issue (and the fan will automatically ramp up to high speeds as needed), but even if it could not, it would still work just as well for my application. IE, there would be no change in the way the system works for me if the fan was simply removed altogether.

I run a AII 240 at stock clocks on a gigabyte ud3 785G motherboard. antec p180, a big xigmatek cooler and no fans. SSD, sata DVD and momentus 5400.6 320gb hdd

2x2gb of ddr2 I *think*, maybe 2x1gb


idles around 30w w/o undervolting

I think with the Thermalright HR-02 you can run most modern CPUs fanless and it's really not that huge compared to other passive beasts.