I don’t want to just grab any mongo-large wattage power supply online. I want to understand how to calculate a reasonable power to component ratio. I really want to try out one of those hdplex power supplies.
You can find PSU calculators online, they tend to overestimate quite a bit.
A good power supply can be run close to its maximum no problems but a cheap nasty one will catch fire around 75% load. If you care about power efficiency then generally speaking power supplies are most efficient at 50% load so if you figure out what your average load is going to be and get a PSU that’s twice as powerful that will be the most energy efficient. Most PSUs will have a graph showing their efficiency curve so you can get a better idea of the range that’s most efficient.
I totally agree with this statement but let me modify this a bit. Figure out what 90 percent of your workload will be and try to figure that around 50 percent load… this will maximize your efficiency but if you get something thats 80P platinum or titanium you will also want to optimize for a second load point and thats the 10 percent heavy or max loads that youll put on it and you want that to be around the 80 percent load area … which will make the power supply most efficient at handling everything you do
Most of the common ATX power supplies will be massive overkill for that machine. Going by the 16 watt TDP CPU, you would probably be hard pressed to break 50 watts unless you install enough fans for takeoff or enough lights to blind people. Given the very low power usage of the machine I wouldn’t even bother with a calculator. Almost anything with an ATX power connector is going to be sufficient.
My experience has been that typical ATX power supplies aren’t terribly efficient that low (RANT - It irks me seeing sites trying to measure power consumption on low end machines with their test bed made for high end gaming rigs and an ATX PSU capable of several hundred watts /rant). I have a handful of machines running on PicoPSU’s that average about 10 watts less power draw compared to running the same machines on various ATX PSU’s. I have a couple Intel Atom machines (J1900, N3150) with a couple drives and a bunch of USB stuff, and at max they barely hit the low 20 watt range according to my Kill-A-Watt meter. My HTPC is a Haswell Celeron G1850 undervolted with a 53W TDP that runs ~30W idle and ~40W full tilt, also with 2 drives and a bunch of USB stuff. Those machines plus some that have been retired all ran about 10 watts higher trying various ATX PSU’s.
I’m about to be grabbing another PicoPSU for my mother since finding her old Sandy Bridge machine with a dead PSU fan and the faint smell of electronic death. It’s a simple machine just using the iGPU and I stole a PicoPSU from another machine to test it with and had no issues. I didn’t have the watt meter on me at the time, but the kit I have used on a number of machines is this one:
I grabbed that kit for one machine about 3 years ago and it still works great. I’ve grabbed a few more since then. I originally got an M3-ATX from those guys somewhere around 10 years ago or more and that still works as well. I’ve used it with a brick and with solar and never had an issue. The low heat, no noise, and lower power consumption pairs very well with low power draw machines.
The only two issues some people might have are the power connectors and the brick. Some people get absolutely enraged by power bricks and I guess this just isn’t for them. If you need different power connectors then you can go with a bunch of adapters or just solder on what you need. I’ve had no problems adding SATA and P4 power connectors by soldering them in. After one bad incident with a molex to SATA adapter going up in smoke I try to avoid them when I can.
I know there are other brands and I haven’t really heard anything bad about them. The HDPLEX ones look interesting and have higher output, but they wouldn’t work with either 12V or 24V nominal voltage which kills and mobile or off grid usage and it’s really a shame.
Harddrives and SSDs say how much current they pull from wich rail, mutliply current and voltage to get watt. Then sum up the wattages from all components.
For DDR4, you can go with 4W per stick.
For your parts:
CPU: 16W TDP, assume 20W just to be sure
Motherboard: 35W (assumed) could not find reliable data, also USB 2.0 could provide 2.5W each
RAM: 4*4W = 16W
Crucial MX300: 3.3V * 1.7A = 5.61W
WD Red: 5V * 0.440A + 12V * 0.550A = 8.8W
Most 2.5" SSDs: ~3.5W
Total: 20W + 35W + 16W + 5.6W + (2* 8.8W) + 3.3W = 97.5W
In theory, the system could draw 100W, I would say every higher quality PSU able to provide 80W or more will work.
Unrelated to the PSU question, but might I throw in that the WD MyBook 8TB is cheaper (almost $100) than the standalone 8TB Red drive? WD doesn’t make 8TB Blues or Greens, so the 8TB MyBook should use a Red. Buy that, shuck it (remove from enclosure and use as internal drive) and save some money.