I am looking for a UPS for a threadripper workstation i put together recently. I run this PSU: Seasonic Prime TX-1300 ATX 3.0 - so im drawing less than 1300W. Obviously the biggest power draw is the 5090 but I suspect im never runnign system at load.
Any suggestions would be much appreciated. I would prefer a pure sine wave though.
I happen to have the 230V variant of this APC UPS unit:
No complaints so far 
Got it used (missing the front panel) and I had to replace just the batteries. Having an electronics background that was significantly cheaper then the entire battery pack. IIRC I spend €120-ish for 4 batteries vs a 600€ APC branded battery pack. 
I run a Seasonic Prime TX-1600 ATX 3.0 PSU for headroom on a 7975WX and 4090. Everything overclocked.
I couple this with a CyberPower PR1500LCD Smart App Sinewave UPS.
This is pure sine wave.
https://www.cyberpowersystems.com/product/ups/smart-app-sinewave/pr1500lcd/
You can find it on Amazon Prime for less than MSRP if you search by model number.
+1 on the CyberPower PR1500LCD. Currently running that paired with 3495X + RTX Pro 6k. Can pull more than 1500w with that setup.
My TR system, 5995WX + 3090, is paired with APC Back-UPS Pro 1500. And rack, synology + ubiquity gear, paired with CyberPower OR700LCDRM1U.
Nowadays, I’d forego expensive UPS w/ SLA batteries, and pick up Ecoflow Delta 3 Plus or other LiFePO4 w/ UPS capabilities. One friend is using that setup and recommended it to me. He lives deeper in the mountains, and experiences more power outages than I do.
I have tried a couple of ecoflows up to the delta pro and unfortunately when they switch between grid power and battery power the voltage drop is long enough to crash my thread ripper box so I ended up sticking another ups between the threadripper and eco flow since the eco flow is also my solar inverter
I’ve been using a Bluetti AC500, It doesn’t seem to notice drops in the source at all. I’m pretty sure it always drive the output via the inverter and uses the battery as an always active buffer. Downside is a fairly high (for a UPS) parasitic energy use which leads to a fairly loud fan at times.
It also solves the problem where the computers and accessories can pull enough power to trip the breaker. I set a max AC draw (1500w), and it can output up to 5kw if needed.
Yes it’s overkill but it’s 2nd purpose if to provide power in case of blackouts. In turn it would charge from the EV.
Blueetti was going to be next on my list of things to try but other then the voltage drop issue which is only a problem when I’m pulling 1500w on the workstation it works well. Gives me 12 KW of battery backup, handles my solar, time of use power offsetting, and is generally not something I have to think about. Maybe in 4 or 5 years I’ll start shopping around again and see what the market looks like then.
Obviously this calls for a server rack lithium battery! 
(Combined with maybe a Victron inverter or something like it.)
Edit: Heck, there are even 48 VDC input PC power supplies! No inverter needed, “only” a battery charger!
(Note: I have no experience with any of this. Just making a bad joke while supplying some links that might possibly be of interest.)
Certainly is! Now if only those prices come down
1300W rated power means ~1400W from the grid.
Pencil it out:
8W per RAM-stick
CPU?
600W GPU
5W per M.2 SSD
HDDs?