Way overkill. Get a Celeron instead.
Yeah, but the problem is I can't find a single Celeron for 1156, I would have to import it and postage would make it more expensive than said i3. Same if I wanted to use 1155 boards - more expensive (I can have this 1156 Gigabyte for about $50 and 1155 boards run twice as much). This setup has the best cost among things I could find.
Cheapest used 2x2 GB RAM I can find
Overkill. And would waste power. Use a single 2G or something.
I forgot - I'll be running many torrents at once too, with 150 Mbit/s Internet it can make CPU, RAM and disk all a bottleneck, especially the disk, but I want to eliminate the possibility of RAM interfering too and be able to adjust the amount of files opened at once. 4 GB should be enough and I ran into problems with 2 GB before.
Not sure the wattage would be all that low. And it might run hot.
Asus used to sell a low-power version of the same thing but I don't know if it's got USB3.
I believe it is low power. I crunched some numbers and googled it up a bit, depending on PSU the measured wattage (both idle and load) of the E45M1-M is much lower than the abovementioned i3 setup (about 25-40 W idle and 40-65 W loaded, Clarkdales can't even dream of such figures). Now, obviously, if I were to buy a LGA 1155 board then I'd have access to a low-power i3, which would be comparable (though still a bit more power-hungry) in terms of power consumption, but also more expensive.
Having calculated this I think I just became more swayed towards the AMD solution. The only thing that's keeping me back is the speed because I have doubts that the E-450 is up to the task, especially if I, for example, had xx torrents open, watched a video from my desktop and copied files at the same time. I know my single-core Atom 1.6 would collapse under such load.
Low-end Intel and MSI boards for Clarksdale onwards used to pretty energy-efficient if you want to look for a used board. Again, I have no idea what's got USB3 since I'd rather use eSATA.
This Gigabyte is the cheapest Clarkdale with USB 3.0 I could find. And, unfortunately, I have a lot of quality USB 3.0 SATA enclosures and high-speed pendrives, which I'm not willing to exchange.
Boards with DC input should be silent. Powering two 3.5'' drives might be a problem however.
That's a bummer.
I think your main problem will be finding a silent ATX PSU. Availability and prices suck in many locales but if you're OK with picos you should be able to find them globally on eBay. Try to get it from a reputable seller though. And get a quality AC/DC brick!
Thanks. Will a 120W PicoPSU be enough for two 3,5 drives?
Get very quiet drives and the case won't be much of an issue.
If you're handy and the case is big enough, there are ways to dampen drive vibrations. Dumpster-diving could get you a suitable case.
I'm mostly worried about cooling, because I want to have as few fans as possible and cheap cases tend to have bad airflow, so this would be the one thing I won't be saving much money on.
a mSATA slot
Pointless: boot from a small partition at the beginning of your big hard drives. Boot would be somewhat slow but such devices are typically rarely booted so...
Oh, I wouldn't use it for booting, but as a torrent cache drive. Downloading torrents @15MB/s can bring even very good platter drives to their knees. I can live without it though, there are other solutions.