this post was submitted on 19 Nov 2023
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I recently had my basement rewired and have a 20A circuit breaker with 12 ga wiring to outlets with two 5-15 receptacles. I'm looking at getting a Liebert GXT3 UPS and having a hard time figuring out which variant I can use with my Dell R730. The power supplies that it came with are each labeled 750W, 80+ platinum efficiency. I can add, so that looks to me like I'll need the GXT3-1500RT for a UPS and I have been told I need to have a bit of headroom on that, but the 2000RT variant datasheet indicates it uses a 5-20P plug which isn't going to work with the outlets I have.

Will a 1500 work for me or do I need to buy two 1000 flavors instead? Is an GXT-1500 going to be sufficient for an R730? I have no idea how much power the server actually draws - those 750W are the power consumption when the supply is pushed to the max, right? The baseline level I need to provide a UPS for doesn't have to match that (plus 10%) all the time does it?

I appreciate any help anyone can give me on selecting a UPS; I don't want to exceed what my wiring is rated for or do anything crazy, I just want to make sure I don't spend a bunch of money on a UPS that isn't going to do what I need or won't work with my setup. Thanks.

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[–] [email protected] 1 points 10 months ago

A 1500 should be fine for you.

Your R730 can be configured in either redundant mode or non-redundant mode for power in the iDRAC settings. If you have it set up as redundant, it will use up to 750W (give or take a small amount for power conversion inefficiency and such) since a single power supply would need to be able to support the entire server if the other went down. In non-redundant mode, you can use up 1500W (again, give or take a small amount) but if one power supply goes down the entire system may go down (I've never personally tried this so not sure what actually happens).

You can also set a power cap in iDRAC settings as well if you want to be extra cautious - this is the maximum power it'll use (give or take a small amount again).

I have a 1500W CyberPower unit that I use for my R730 with dual 750W power supplies (in redundant mode) along with several other things (other servers, networking equipment, tape drives, etc). I draw about 400-500W depending on what I'm doing. I don't use any of the power capping features so theoretically I could exceed the maximum output of my UPS if I were to push all of my stuff to 100% usage but I never do that so it's not an issue for me.