Suggestions for a UPS (200$ max)

[ThunderZed]

I've built this basic PC desktop:
- Corsair CX450 PSU (OEM CWT RPS0053) with active PFC = 450W max
- CPU amd ryzen 2200g = cTDP 46-65W
- mobo msi b450-a pro = honestly I don't know how much Watts
- ram HyperX Predator DDR4 HX432C16PB3K2/8 Kit 8 GB (2 x 4 GB), 3200 MHz, DDR4 CL16 DIMM = I don't know exactly but I guess about 2x1.5W = about 3W
- hdd WD black @7400rpm (WD1003FZEX-00K3CA0) = 6.8W (read/write)
- monitor Acer x193w = 37W
- other stuff: basic mouse + basic keyboard + case (Sharkoon S25-w with 2 fans) = I guess just a couple of Ws
TOTAL = 111.8W for sure + mobo + other stuff = I guess it's all under 200W at max load.

Now I need a UPS but my budget isn't high enough to get the best (eg. an online UPS) so I'd like to buy a UPS with the best quality/price relationship for my goals and my PC. I don't want to spend more than 200$.
AFAIK I need a UPS that generates a pure sine wave during a blackout because of my PSU's active PFC, else please correct me.
My goal is just to preserve my PC's health from surges, brownouts and blackouts. My worst scenario is when it's raining hard because blackouts occurs randomly and sometimes quite close one to the next one, definitely I need a UPS that lets me shut my pc off correctly for 2 times (blackouts) in a row close 30 minutes the 1st one to the 2nd one.

My milestone is cyberpower cp900epfclcd, here you can get its specs, eg.: VA 900 - Watts 540 (Output Power Factor 0.60) - Line-interactive UPS Topology - Active PFC Compatible - Pure Sine Wave Output, Automatic Voltage Regulation (AVR). Its current price is 200 euros (equal to 200$).
Consider I live in Italy so I can't buy, eg., cyberpower CP850PFCLCD because it's not available here nor APC BR1000MS which generates pure sine wave as well.

Finally I'd want to tell you a problem of this PC because I guess it can be related to the UPS.
I've been using a very cheap (but loaned) 800VA UPS, so bad that its datasheet didn't say what kind of output wave it generated. Almost every time a blackout occurred and this UPS supplied my PC, it happened that my PC didn't boot: I switched it on but I got only a black screen. The only solution I found was to open the case and disconnect my hdd sata plugs, then it switched on. Of course I had to switch it off directly by the power off button, than connect the hdd plugs back again and then it booted.
My guess is that cheap UPS was the culprit so I think I need a pure sine wave UPS to supply my Corsair and avoid this problem. What do you think about that?

[NiHaoMike]

Get a used rackmount UPS for cheap and replace the batteries.

[pqass]

I don't think a pure sine wave UPS will matter much to the switching power supply of your PC.

I've used the same APC Back-UPS XS 1300 LCD "Stepped Sine Wave" UPS since 2007 without it affecting the load. My load is only 150W and the UPS is rated for 780W (as read from the UPS by the apcupsd software that I use).  I purposely bought more than my need so that I don't over-tax it.  However, the two 12V 7Ah batteries didn't last more than 3.5 years; and I've done three pack replacements since. The last replacement two years ago I opted to instead attach an external (2x) 12V 18Ah pack thinking that the larger pack will cope with the abuse and thus last longer. So far, so good. If curious, see write up here: https://www.eevblog.com/forum/projects/pitfalls-on-substituting-larger-ah-battery-pack-(with-same-voltage)-on-ups/msg3145170/#msg3145170

I really don't see how booting without the HDD, then reconnecting and rebooting would matter.  I'd be sooner think that the PS wasn't properly shutdown and a hard (rear switch or plug pull) restart was needed. Did the UPS cut power after running out of battery capacity OR did your software initiate a soft power off?

[pcprogrammer]

I'm using "Eaton Ellipse"  UPS models for my computers. Not pure sine wave on the output, but they keep my computers running during blackouts. Long enough to finish something and turn the computers of when the blackout starts to last more then 20 minutes.

Have not tried booting the computer on just the backup power, because well that is not what an UPS is for is it?

Reading your story about having to disconnect the hard-disks makes me think the UPS you have chokes on the startup current of the computer, which might be much higher then the normal operation current.

Take a look on their website. https://www.eaton.com

[james_s]

I don't think a pure sine wave UPS will matter much to the switching power supply of your PC.

It does matter if it's like many PC PSUs today that have active PFC, although a stepped sine wave might work, the common "modified sine wave" (square wave with dead time) will not work properly.

I have one of the Cyberpower ones the OP mentions and it's been fine. I have my tv, media center and floor lamp plugged into it, I originally got the pure sine model because the floor lamp has a dimmer and would shut off whenever the UPS kicked in.

As a side note, plugging lamps into a UPS is great, it gives you automatic emergency lighting without needing to install a dedicated emergency light.

[Helio_Centra]

you can probably get a used one for cheap then just replace the batteries.

[pqass]

I don't think a pure sine wave UPS will matter much to the switching power supply of your PC.

It does matter if it's like many PC PSUs today that have active PFC, although a stepped sine wave might work, the common "modified sine wave" (square wave with dead time) will not work properly.

I have one of the Cyberpower ones the OP mentions and it's been fine. I have my tv, media center and floor lamp plugged into it, I originally got the pure sine model because the floor lamp has a dimmer and would shut off whenever the UPS kicked in.

Investigating further into the issue...
I came across this marketing blurb: "Shutdown can occur because simulated sine wave output has a power gap in each cycle. When the UPS system switches to battery current, a power supply with an Active PFC circuit may detect that power gap and shut itself down. "   Here: https://www.synnexcorp.com/us/powersolv/wp-content/uploads/sites/105/2021/03/CyberPower_Active-PFC-Whitepaper.pdf

I would consider it a design fail if a newish active-PFC switching PS could not cope with the cheapest desktop UPS (400VA class).  This would result in a lot of PC returns.  There is an expectation that PCs may be attached to UPSs whereas dimmable lighting, not so much.

[james_s]

Investigating further into the issue...
I came across this marketing blurb: "Shutdown can occur because simulated sine wave output has a power gap in each cycle. When the UPS system switches to battery current, a power supply with an Active PFC circuit may detect that power gap and shut itself down. "   Here: https://www.synnexcorp.com/us/powersolv/wp-content/uploads/sites/105/2021/03/CyberPower_Active-PFC-Whitepaper.pdf

I would consider it a design fail if a newish active-PFC switching PS could not cope with the cheapest desktop UPS (400VA class).  This would result in a lot of PC returns.  There is an expectation that PCs may be attached to UPSs whereas dimmable lighting, not so much.

Look at how an active PFC correction circuit works, they were not designed to run off a square wave. Active PFC was uncommon in the era of square wave UPSs, now sine wave units are inexpensive and readily available, I see little reason to get anything else now. It's not like you have to spend a fortune, they're about the same price square wave UPS's were a few years ago. Mine was under $150 brand new.

[ThunderZed]

One of the things I haven't still understood from my researches about UPSs is the "limit" an "approximated" sine wave form is "enough" for my personal scenario or not (ok, I'm a very newbie anyhow!), in the sense it won't damage my PSU/PC throughout long time, due to that I wrote as many details as I know about my cfg and the last "issue".
I know a pure sine wave is better for sure but the UPSs that generates it are more expensive than the simulated / stepped approximation to sinewave ones. Of course you can get a cheap pure sine wave UPS instead of an expensive approximated sine wave one but I guess the electronic component quality inside the UPS matters very much. I give you an example of a cheap "pure" sine wave UPS available here in Italy: powerwalker VI 600 SW IEC. You could buy it for about 90$ on amazon.it last year *but* look at the oscilloscope graphs got by this german final user in attachments. Ok, we can't be sure of his/her "honesty" but let's take it as an example and answer my question: will this kind of waves damage my PSU (or my other PC equipment) on the long time?

Reading your story about having to disconnect the hard-disks makes me think the UPS you have chokes on the startup current of the computer, which might be much higher then the normal operation current.

Just to see if this booting problem is related or not with (cheap) UPSs: consider that for first I tried to bypass the cheap UPS connecting my PC (PSU, monitor, etc) directly to my electrical line but I couldn't solve. I tried different solutions before finding the "right" one I told you above, anyway I don't know if that is the nly solution or not.
This booting problem occurred sometimes in the past before using that cheap UPS and I related it to surges/brownouts but it's only a sensation and I can be wrong. If there's something right in my ipotesis I think it will be better to avoid too "bad" waves not to worsen my PSU's health.
I only add I've to unplug my internet key usb from the rear of my case along with sata connectors from its inside to let my PC boot.
Am I on the wrong way?

Get a used rackmount UPS for cheap and replace the batteries.

Do you mean "online" (double-conversion) for rackmount? Honestly I've never bought anything used of IT/electronic equipment because it almost depends on its usage, I mean who and how used it, and I've always thought it's too risky. Just as a curiosity I show you the only used online UPS available within 200$: a 170$ (=150+20 shipping) refurbished Xanto RS 1500.

[james_s]

Do you mean "online" (double-conversion) for rackmount? Honestly I've never bought anything used of IT/electronic equipment because it almost depends on its usage, I mean who and how used it, and I've always thought it's too risky. Just as a curiosity I show you the only used online UPS available within 200$: a 170$ (=150+20 shipping) refurbished Xanto RS 1500.

IT grade equipment is very well made, and generally set up and used by people that know what they're doing, as far as quality goes used gear like that is the best you can get. I wouldn't buy it for home use though unless you have very cheap electricity because efficiency is not usually the primary concern. A good consumer UPS will draw under 2W of standby power, a big rackmount UPS can draw 10 times that, and a double conversion type will draw even more.

[ThunderZed]

a big rackmount UPS can draw 10 times that, and a double conversion type will draw even more.

As said above I'm very newbie, if you make this difference between rackmount ups and double conversion ups I guess I was wrong when I supposed rackmount = double conversion, right? So what's the advantage to get a "not double conversion" rackmount?

I wouldn't buy it for home use though unless you have very cheap electricity

I think maybe this is an interesting question to evaluate for me related to my booting problems. As said above they also occurred before trying that cheap ups, I mean can low electricity quality be the culprit? If yes maybe a double conversion ups will solve this problem but I've to understand if there's a relationship between electricity quality and my booting problem for first. Do you think it's better if I open a new thread for my booting problem before choosing my ups?

[james_s]

As said above I'm very newbie, if you make this difference between rackmount ups and double conversion ups I guess I was wrong when I supposed rackmount = double conversion, right? So what's the advantage to get a "not double conversion" rackmount?

No, they are two different things, although most double conversion UPS's will also be rackmount. It's more of a professional vs consumer thing. A professional IT grade UPS will be optimized for different things, generally the power consumption will be higher and they don't have to meet the consumer energy efficiency laws.

[nctnico]

a big rackmount UPS can draw 10 times that, and a double conversion type will draw even more.

As said above I'm very newbie, if you make this difference between rackmount ups and double conversion ups I guess I was wrong when I supposed rackmount = double conversion, right? So what's the advantage to get a "not double conversion" rackmount?

The first question you should ask yourself is: do you really need a UPS? A very long time ago I have been using UPSes for a while but quickly learned that they caused more outages (due to needing battery replacement or failure) than they helped prevent. Better make sure you use a journalling filesystem that can repair itself. I see you bought an old fashioned hard drive; I would return it and spend the money on an SSD. That is a way more worthwhile thing to spend money on; both speed and noise will improve drastically.

If you want to work through an outage, simply use a laptop.

[SiliconWizard]

a big rackmount UPS can draw 10 times that, and a double conversion type will draw even more.

As said above I'm very newbie, if you make this difference between rackmount ups and double conversion ups I guess I was wrong when I supposed rackmount = double conversion, right? So what's the advantage to get a "not double conversion" rackmount?

The first question you should ask yourself is: do you really need a UPS? A very long time ago I have been using UPSes for a while but quickly learned that they caused more outages (due to needing battery replacement or failure) than they helped prevent.

Uh. Buy something that works, then.

Years ago I was in an area where power outages were extremely rare, maybe once a year if so, and often due to an incident such as fire. I had no UPS and that never caused any issue.

But where I am now, otages are "very" frequent. Most don't last long - a few seconds to a few minutes max. Without a UPS, I would be in trouble. The UPS I am using is about 10 years old and works flawlessly. I had to changed batteries once after about 5/6 years. Next change may be soon. Definitely worth it. And uh... these days, outages are possibly going to be even more frequent everywhere. So...

[james_s]

But where I am now, otages are "very" frequent. Most don't last long - a few seconds to a few minutes max. Without a UPS, I would be in trouble. The UPS I am using is about 10 years old and works flawlessly. I had to changed batteries once after about 5/6 years. Next change may be soon. Definitely worth it. And uh... these days, outages are possibly going to be even more frequent everywhere. So...

That mirrors my situation. During the winter when it's stormy I have quite a few power glitches that are just enough to reboot everything. Then usually once or twice a year there is a longer outage, a couple hours to a day, in that case the UPS's give me time to get out the generator and set that up at a leisurely pace. My RPi server uptime is almost 600 days, my router, security cameras and recorder and Plex server are all on couple UPS's and there is another one on my TV, media center and the floor lamp. I've never had any trouble with any of the UPS's I have in service.

[ThunderZed]

No, they are two different things, although most double conversion UPS's will also be rackmount. It's more of a professional vs consumer thing.

So is the advantage of a used online (aka double conversion) pure sine wave rackmount ups (like the Xanto RS 1500) its reliability in comparison with a brand new average-quality "domestic" pure sine wave one (like the cyberpower cp900epfclcd)? What about in the long time working comparison? I mean in 10 years will their maintenance costs be the same? In other words will they have the same probability of breaking down? If the xanto will stop working for a damage (eg. a broken cap or other reasons) will it be as easy and cheap to repair as the cyberpower?
I ask all these questions because this UPS is an investment for me in the long time and now I want to spend my (few) money in the best way for my future.

What about the VA/W I need? I know "the more VA the better it is" but what's the minimum for my equipment? I think 850-900VA can do the "job" now because my goal is that in 5-6 years its battery has to be still able to supply my equipment for one minute or so during a blackout, just the time to switch off those 120-140 Watts my PC uses. What do you think?

[james_s]

Commercial IT grade devices will generally be much higher quality but even most consumer UPS's are very reliable, the thing that usually fails in both is the batteries. Larger units will have larger/more batteries that cost more.

The VA you need depends on the load you plan to run. If in doubt, use one of those Kill A Watt type devices to measure the power, or even just use a true RMS DMM to measure the current since that will get you VA which is what you need in this case.

[SiliconWizard]

Yep. When selecting UPSs, look for replacement batteries and see if they are easily available.

[james_s]

Something I forgot to mention about the capacity, the ratings at least on consumer UPS's are usually very optimistic. If you actually try to pull 800VA from an 800VA UPS it will be drawing 30-40 amps from those poor little SLA batteries and will fully discharge them in just a couple of minutes, that's brutal treatment. Personally I try not to load a UPS up to more than about half the rating.

[ThunderZed]

I'm using "Eaton Ellipse"  UPS models for my computers. Not pure sine wave on the output, but they keep my computers running during blackouts. Long enough to finish something and turn the computers of when the blackout starts to last more then 20 minutes.

My very first goal is to preserve my PC's hw health from brown/blackouts, especially my mechanical WD hard disk. Afaik as soon as a brownout occurs its plate spins slower and its head scratches the plate so it's worse than a blackout.

Few months after I built this PC I emailed corsair to ask them suggestions about the shape form an UPS that supplies it must have and they replied:

If you wish to purchase a UPS to have your system plugged into we recommend that you stick to a sine wave UPS.

What exactly does "sine wave" mean? "Pure sine wave" or just "approximated sine wave"? I think you can interpret it how you prefer!

[james_s]

What exactly does "sine wave" mean? "Pure sine wave" or just "approximated sine wave"? I think you can interpret it how you prefer!

Pure or approximated sine wave will probably work fine. What you can have issues with is "modified sine wave" which is not actually anything like a sine wave at all, it is just a square wave with some dead time so that the peak and RMS values are similar to that of a sine wave.