I'm looking to build a cheap but expandable server I can set up in my basement and use to store backups, stream media (Plex), and perform other miscellaneous services on my network.

While I haven't had much trouble choosing other parts for this build (hard drive, case, power supply), finding a good CPU has me feeling a bit overwhelmed. There are just too many factors that go into determining CPU speed for me to easily judge based on specs alone.

What's a good, budget CPU I can use for this purpose? It needs to be fast enough to do on-the-fly media transcoding for Plex, and I want it to be power efficient since I plan to be running this server 24/7, but aside from that cheaper is better. Integrated graphics would be a nice bonus since it would save me from having to purchase a video card separately, but it's not strictly necessary as I can get a cheap video card for ~$35 anyway (the server will usually be running headless, so I don't need anything fancy as far as graphics go).

  • What motherboard do you have? That was greatly influence what CPU you can get.
    – Andy
    Oct 11 '15 at 1:02
  • @Andy I haven't chosen a motherboard yet. My plan is to pick the CPU first and then pick out a good motherboard that's compatible with it.
    – Ajedi32
    Oct 11 '15 at 1:03
  • The transcoding will be the worst thing you do, but it will depend greatly on what formats, resolutions, and frame rates you are transcoding from and to.
    – James
    Oct 11 '15 at 3:07
  • @James Yeah, unfortunately I'm not exactly sure what formats and resolutions I'll be using. Probably not 4k, but aside from that I'm not really sure.
    – Ajedi32
    Oct 11 '15 at 3:09
  • @Ajedi32, you need to decide on your formats before you can know what CPU is required. An Intel Atom CPU can transcode to 320x240 MPEG-1 without breaking a sweat; at the other extreme, a six-core i7-3930K cannot transcode to 2048x1536 h264 in realtime.
    – Mark
    Oct 11 '15 at 4:06

Plex suggests a passmark score of >2000, and suggests a core2duo at 2.4ghz as a minimum for a single 1080P stream.

I initially looked at the modern 'atom' architecture celerons but they're a bit too weak. If you didn't need realtime, 1080p transcoding they're excellent.

As such at modern processors a dual core 'pentium' based off a 'core' architecture would be a great option. I'm sure someone would suggest an AMD equivalent, which would likely be price and maybe even performance competitive, but as is, intel makes more efficient processors, and well, I'm familiar with them.

Lets talk about right now. I tend to use the falcon logical increments guides as a starting point for a new build. There's a minimum build based off the intel G3250, and that exceeds the necessary passmark score. Dual cores, and if you drop the add on GPU, the whole build is under 300 dollars.

For near future use, the dual core, dual thread G3470 looks like a good option. It's based off skylake (so you can take advantage of all the lovely new features the newer board will have). The Passmark score for the G3470 is 3,753. While this is a 'next generation' part, for a line that's just trickling into retail, its worth considering this would be a future proof design, which you can upgrade to the next generation, and motherboards may support newfangled things like m.2 and DDR4 optionally. I'd actually have recommended a G3270, if it existed.

  • Ah, yeah that Falcon guide definitely looks useful. I have been looking into AMD processors since they have a reputation for good multi-core performance per dollar, but I also got the impression that intel CPUs tend to be more power efficient. Future-proofness (if that's even a word) is also important here, so I'll definitely look into the parts you mentioned.
    – Ajedi32
    Oct 29 '15 at 13:20
  • Quite honestly, Picking a CPU is far more complex than it used to be. Back in the day you just picked the most clockspeed for your money and you were done ;) Oct 29 '15 at 13:37
  • Yeah, that's why I ended up here. Initially I was just using PCPartPicker, but I found that wasn't very good for comparing CPUs since it doesn't have benchmarks or any other good way of comparing CPU performance. That's when I came here. I've since discovered cpubenchmark.net which is good for comparing performance of CPUs, but not as good at comparing other factors as PCPartPicker is, and now looking at the Falcon guide it seems like that might help as a good starting point. Still really tricky though...
    – Ajedi32
    Oct 29 '15 at 13:46

Since streaming is a decently multithreaded application, I'm going to go ahead and suggest an AMD equivalent, the Athlon 860K, based off the Steamroller architecture. It is an unlocked CPU, dual-module, 4 CMT cores, with a passmark score of 5617, it shouldn't be much more expensive than the Pentiums. If you want a iGP, the A8-7670K is my recommendation, priced about $20 more. Note the CPU would be slower because it has to share TDP with the graphics. Otherwise, you can purchase a discrete GPU.

I'd suggest a cooler to go with the CPU as well, something like the Cryorig H7, to move the 95 W of heat away. You may even overclock a bit.

The Athlon and A8 both use DDR3 RAM. If you choose the A8, be sure to get fast RAM, because the iGP would perform significantly faster.

Overall, the AMD should be slightly more expensive, and also slightly faster.

  • Interesting. You make a good point about AMD processors' multicore performance. I am a bit concerned about the power efficiency though given the TDP of those CPUs. I'm also not too sure about the potential for future expandability, as I haven't seen a lot of faster AMD processors using the FM2+ socket. (Meaning I'd have to replace the motherboard to upgrade, right?)
    – Ajedi32
    Oct 30 '15 at 14:13

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