After going over the hardware selection in my previous post, we still need to get power to the servers…
The power system is going to be a difficult part of this build… As I wrote earlier, I am not a DYI person and I’ve been on the receiving end of enough electric shocks that, frankly, electricity scares me. But there is no way I can use discrete power supplies for every motherboard because:
- every power supply would need to be (slightly) over-dimensioned
- every power supply is an AC/DC converter which is wasteful
- it would be too expensive
- it would require too much space
Can I use a PC power supply?
My first idea is to simply use a regular, beefy computer power supply and figure out a way to use it to power multiple servers. Sadly though, a PC power supply has a specific cabling setup that is ideal for one PC, but that not easily lends itself to what I need.
My boards only take one power feed between 9V and 19V. Basically, this means that all the 5V leads are pretty much useless and the 20V leads are too hot. Possibly 20V might still be usable, but these boards are usually fed using 12V power bricks. 20V will, if the boards do not blow up, significantly shorten their expected lifespan.
Now people have used regular power supplies and are still doing so, but the modification work seems way too much work to me and the end result is not exactly pretty, in my opinion.
Using a “generic” power supply
So I need to go way out of my comfort zone and get a simple power supply that takes 220V AC and gives 12V DC out. Some internet searching leeds me to the MeanWell site. Apart from the friendly name, I can find a lot of good reviews of their products and they seem to have a very wide product range. After reading and comparing a lot of product data sheets, I decide on the MeanWell RSP-500-12 AC/DC 500W 12V/41.7A.
- it is very small, only 230x127x40.50 mm
- it gives the 12V I require on three output terminals
- I figure each board will need about 1 Amp, so 41.7 Amp should be ample to feed the boards
- I expect to only need about 250W power, so a 500W power supply should definitely be enough
- it has active PFC (Power Factor Correction)
The three 12V output terminals should be plenty since I have pretty much decided to make two cabinets of six motherboards each. Looking at the motherboard, I expect a six board housing to be a nice little cube. The power supply will power two (and in future maybe three) compute “pods” so it needs to be external in it’s own little case.Great! Looks like I am going to be making three cases now… :s
Additional purchases include some cable shoes to put on the 220V cable to the power supply, a crimping tool for the shoes and 56 spacers which I think are a good idea to make motherboard “stacks”.
Total spend so far
I am going to put this in a table now. I’m also splitting the costs in a few categories to have a good idea of where the money is going.
Sadly, adding the switches and the power supply did break my 2.000,00 EUR budget for the server hardware. But I do think I won’t be adding anything else to that category so I can live with it.
|CarTFT.Com||Mitac PD10BI Rev 1||Intel Bay Trail Celeron J1900 4×2.42Ghz||12||72.70|
|SiComputers.nl||CT51264BF160BJ||Crucial PC3-12800 4GB||24||23.50|
|SiComputers.nl||WD5000LPVX||Western Digital Blue 500GB SATA 6Gb/s||12||42.50|
|Routercenter.nl||GS108GE||Netgear GS108 8-Poorts Gigabit Switch Duo Pack||1||73.00|
|eoo-bv.nl||DA5M3X40||Afstandsbus 1x binnen-1x buiten M3 40mm||56||0.27|
|Conrad.nl||1293106||MeanWell RSP-500-12 AC/DC 500W 12V/41.7A||1||141.14|
|Conrad.nl||1082735||DC aansluitkabel tweelingkabel||13||2.30|
|Conrad.nl||735440||Ringkabelschoen blauw 1.5 – 2.5mm M3.5||8||0.63|
|Conrad.nl||735327||Ringkabelschoen rood 0.5 – 1.0mm M3.5||8||0.52|
|Conrad.nl||1218498||NK 103 S-500 5mm Zwart||1||9.99|