I have two main work PCs - my Windows desktop and my self-built Windows Home Server. I also have a media PC, but as all its data is stored on the WHS box, it doesn’t really need a UPS. Using my Maplin plug-in power meter, I found that the desktop (which has a 2.93GHz Pentium Core 2 Extreme X6800 CPU) averages out at around 120W in use, and the WHS box (with a 3.4GHZ Pentium 4 Extreme Edition) rarely moves above 80W.
I also wanted to protect my Acer X223HQ 22in monitor, which uses about 60W maximum, giving a total of 260W. Doubling this to give some extra running time on battery meant I needed a UPS with a rating of about 800VA (using the rule-of-thumb of multiplying the VA figure by 0.6 to get Watts).I had to brush up my fading memory about the different types of UPS, and I got sidetracked for a while reading about ‘pure sine-wave’ line interactive models. This is pretty much a red herring for the average domestic user - the ‘stepped approximation to a sine wave’ (or ‘simulated sine wave’) output used in most low-cost standby (off-line) models is perfectly fine for the vast majority of users. My PCs both use modern, good-quality Active PFC PSUs from BeQuiet, and they weren’t fussed by my eventual choice of a model with a stepped output.
The confusion arises because some PC PSUs using active power factor correction (Active PFC) can trigger an overload condition on some UPS models when they turn on - APC has an explanation in its knowledge base. All PSUs sold in Europe have had to use PFC for many years, but most use passive PFC, which is a little more tolerant of stepped waveforms. If your PC has an Active PFC PSU, it should be fine, but if it generates overload trips, or turns off when the UPS transitions to battery power, this could be the reason.
Eventually I decided on a Cyberpower GreenPower DX800E standby UPS from Ebuyer, as it was on special offer (£67 including VAT) and matched my needs. It has three AC outlets (two standard UK 13-amp sockets and one IEC socket) and is remarkably small, measuring 235 x 90 x 190mm - I don’t have a lot of room under my desk so this is a real benefit. There’s just one on/off button, three status lights and a charge level indicator on the top.
|The DX800E is very compact|
After charging it for the recommended eight hours, I plugged it in and everything worked fine. Unplugging the mains kicked the inverter into action as it should. The UPS comes with Cyberpower’s nifty PowerPanel software monitoring tool (the UPS is connected via USB, with a cable included in the box), and I tried this on the desktop PC. For Windows 7 users there’s also a desktop gadget that shows several parameters - input voltage, estimated standby time and so on.
|The PowerPanel software is very good|
|There's also a desktop gadget for Windows 7 users|
However, I wanted to connect the USB cable to my WHS box as this runs 18 hours a day without a monitor, keyboard or mouse and so is awkward to shut down in a hurry. I use the excellent free Grid Junction WHS add-in, which recognised the UPS with no problem. This shuts down the system automatically when the battery drops below 80% charge (which is after about 2-3 minutes with all devices plugged in). I will rely on shutting the desktop PC down manually - when I’m not using it it’s always in hybrid sleep mode anyway, so a loss of power won’t affect it.
|The Grid Junction WHS add-in ensures a graceful shutdown when the power fails|
I’m very happy so far with this bargain UPS, although a minor niggle is that it doesn’t come with an IEC C20 power cable. The battery is supposed to be replaceable, but Cyberpower doesn’t sell these and just says that it uses a ‘universal’ 8.5AH battery. I haven't taken it apart yet, but I reckon it’s unlikely to be cost effective to replace - if I get a couple of years' use out of it I'll be more than happy.
Find it on Amazon:
Find it on Amazon: