Question about UPS systems

[Ciel115]

So I've been having trouble with my Razer Core X eGPU not retaining connection to my laptop (full story) but my local PC repair shop that's been helping me lent me a UPS to try because we suspected it may be an issue of dirty power out of my home's outlets. The UPS appears to have helped because I've enjoyed the most stable connection I've seen in weeks so I'd like to buy one for myself but I'm not sure what I need.

 

The Razer Core X eGPU has a 650W power supply, it's running an RTX 2070 that requires a 550W PSU, but the UPS system they lent me is an APC Back-UPS ES 350VA, 200W. Does the wattage on the UPS only matter when it's running just on battery? Because my stuff is running great on it (while the UPS is powered from outlet) despite the wattage being so much lower than my PSU.

 

Just trying to understand what I need, and if that's different depending if I only care about stable power flow vs if I'm concerned about the UPS powering my hardware in an outage.

 

Thanks!

[PineyCreek]

Might just be the power you've got the eGPU plugged into is dirty/unstable.  The UPS is going to route the power through itself...depending on the type of UPS, it can clean up that power but the Back-UPS ES is a low-end unit so :: shrug :: I dunno.  Trust your results and/or experiment further.  Its power output by virtue of it routing through the UPS could be helping.  If you wanted to test further you could, for example, test your eGPU at another location without the UPS to see if you go back to having stability issues.  The ratings on the UPS I don't think will matter much when the UPS is not actively providing power from its battery.

 

If you planned on purchasing a UPS, you would want to size it such that your maximum wattage used by your connected electronics does not exceed the UPS's maximum wattage rating, and in fact you'd likely want to oversize it to give yourself some headroom for growth.  That being said, what you're actually using at full load is very unlikely to be what the recommended PSU is for the eGPU, etc.  If you want to know how much you're actually using, get a measurement tool, run everything through it (ex. a Kill-A-Watt) and see how much you're actually using at load (ex. while doing fast-paced gaming where your eGPU is actually working hard).

[Ciel115]

Yeah in my house (starting not long after a storm caused an outage) it just connects/disconnects repeatedly, and I tried in different outlets around the house, but when I took it to this PC repair shop it ran perfectly with the same cables and everything, then back to not working when I brought it home, so dirty power is what I suspect.

 

I'm mostly just concerned with having stable power to the eGPU, don't really care about it staying on for a few minutes in an outage, and the laptop has its own battery so it doesn't need outage protection.

 

Anyway yeah thanks for answering the question that the wattage rating on the UPS is just what it can support with its battery, maybe i'll try a cheaper one first, as long as it cleans the power going through it i'll be happy.

[akio123008]

14 hours ago, Ciel115 said:

it's running an RTX 2070 that requires a 550W PSU

the graphics card doesn't use 550W, that number is just the recommended minimum size power supply for use with that card, considering you also have other components in the computer. 

 

However your GPU isn't inside a desktop computer so this doesn't apply; you just need enough power to run the GPU, which is far less. For this reason you don't need a 500+ watt UPS.

 

14 hours ago, Ciel115 said:

Does the wattage on the UPS only matter when it's running just on battery?

Yes.

 

13 hours ago, Ciel115 said:

I'm mostly just concerned with having stable power to the eGPU

Well if the power cuts out for a second, or there's a significant voltage dip, the UPS will maintain power on its output, in that sense it ensures "stable power".

 

It's hard to tell what exactly your problem is and if a UPS would help. A normal (line interactive) UPS also doesn't do much when the power is on, it only begins to work once there's a power cut. If you want a UPS that constantly operates you need a so called online UPS, which is very, very expensive. But in that case you do get 100% stable power all the time.

[Ciel115]

Thank you for the answers! I'm also still a bit confused about what the problem is, but for whatever reason the lower-end UPS I was lent, and the nicer one I picked up today, have made my eGPU connect and function normally after almost of a month of instability that I could only replicate at my house, so whatever it's doing I'm happy with it.

 

I decided to get one that's way overkill for my current setup (900W Cyberpower GX1500U) in case I decide to use its potential in the future. I don't think it's "online" but it does have "automatic voltage regulation", maybe that's what I needed.

[W-L]

20 hours ago, Ciel115 said:

Thank you for the answers! I'm also still a bit confused about what the problem is, but for whatever reason the lower-end UPS I was lent, and the nicer one I picked up today, have made my eGPU connect and function normally after almost of a month of instability that I could only replicate at my house, so whatever it's doing I'm happy with it.

 

I decided to get one that's way overkill for my current setup (900W Cyberpower GX1500U) in case I decide to use its potential in the future. I don't think it's "online" but it does have "automatic voltage regulation", maybe that's what I needed.

Units like those are line active units so it will detect when the power quality degrades and kick in the AVR/filter if needed or completely disconnect from the grid if it's really bad until it improves. Those units have a live graph or digital display which you can turn on and see the incoming line voltage and frequency which should give you a quick idea if the wall power coming in was bad. 

 

As for wattage you only need what your system draws so it you have a 600W PSU but the maximum the system consumes is 400W a UPS just larger than that will be enough, more overhead is always better however especially for longer run time if power cuts out.