I’ve always liked rackmount stuff. It was partially because the whole setup could look very organized on outside. And, if you plan to own more than few computers, rackmounting them could make sense.

Back in early 2000s, I used to have my 16U rack almost full with number crunching computers for cancers and whatnot. Fast forward two decades, the rack was empty.

I still kept the rack in my room, only because it was a pain-in-butt to get rid of it. I did get rid of most of my rackmount cases. It wasn’t until December of 2019 that I decided to revive the rack.

You see, my area can get prolonged power outages. It happens at least two times a year, usually a bit more than that. Normally, I didn’t mind too much except the last year’s outage lasted 12 hours in middle of Winter.

This prompted me to think: What if I build a really low-power rig with an UPS attached to it?

For the record, I know that UPS are not really meant for that. It’s usually meant for a PC to have enough time for a graceful power down. At the same time, there is no rules that say a UPS must be used only for that purpose.

So, I drew a plan and began to work on it. I wanted everything within the rack, so I searched for a reasonably priced rackmount UPS. In the end, I ended up with Cyber power OR700LCDRM1U.

1U UPS

The UPS has two 6V 7.2Ah batteries in series, meaning about 84w/h of power. It’s not true sine wave but it didn’t prove to matter in my case. Then there is always some power loss when DC gets converted to AC but let’s not dig too much into that.

84w/h is not much. If you plug a normal PC with 8 core CPU + a high-end GPU on that, it’s going to last few minutes at the best. However, if you plug in a really low power PC, that 84 watt hour could last you easily over an hour.

So, here is the computer I planned and built.

Case: iStarUSA D-214-MATX 2U
Motherboard: Asrock J3455m (mATX)
RAM: Some random two sticks of 4gb DDR3 RAM I had in storage

And there are three expansion cards in this.
Startech m.2 adapter PCI-E 4x
TP-Link Archer T4E AC1200 PCIe
Ziyituod SATA Card

J3455 is a quad core CPU with 10w TDP. I know there are newer models and I really wanted at least J4105 but, being in Canada, getting a hold of them cheaply wasn’t an option. Thankfully, Amazon Canada had J3455 motherboard in stock at 100CAD, so I chose to grab that.

The purpose of this PC is just to play 1080p video files, so RAM doesn’t matter. I used some sticks I had lying around.

The motherboard supports 3 expansion slots at PCI-E 1x speed. Even 1x has got more than enough bandwidth for all those cards I listed. I am using a 256gb NVMe as a boot drive via Startech m.2 adapter.

PSU is actually a SFX one, FSP Dagger 500w. I chose that to save space. The whole chassis is cooled by a single 80mm fan on front. It provides just enough air flow for the passive CPU cooler.

Using IcyDock 4 2.5inch drive bay, I can swap out drives from outside without needing to open up.
I tend to use laptop drives exclusively because you can take them out and power them up with USB power which makes it easy to use them as a backup solution.
Granted, you do pay a little more for the same size but I don’t have that much data to move around. 2TB laptop drives suffice my needs.

The rig draws 28watt during boot which should be the highest it will draw. During a 1080p video playback, it draws 19 ~ 22 watt. Playing youtube draws about 15 ~ 17 since no power is drawn to HDD.
My monitor, a 24inch 1080p, draws a steady 20watt.

So, with 84w/h UPS, the PC should be able to run for about 2 hours.
I haven’t actually tested this yet though. I am going to wait for an actual power outage to test the run time.
However, I did test whether simulated sine wave from the UPS works on both PC and monitor: They do.

So, ironically, I am now waiting for a power outage.