DoctorIkari Posted June 15, 2021 Share Posted June 15, 2021 Hello friends! I recently upgraded my computer for work. Installed the Corsair RMx 850W PSU. In our area, the electricity is periodically turned off, so a UPS was required.I have no experience in selecting a UPS, the store manager advised me to take an APC Back-UPS 850VA (~520W) UPS. After connecting the computer, I decided to test the UPS. I turn off the power, and... the computer shuts down. In the APC Windows utility, the total power during operation is shown as 40-100 watts. Googling suggested that my Corsair RMx 850 PSU has an aPFC. Therefore, the UPS must be selected very carefully. Please tell me which UPS is suitable in my case? Thank you very much! Link to comment Share on other sites More sharing options...
Vegan Posted June 15, 2021 Share Posted June 15, 2021 A UPS is not all that they are cracked up to be. Long ago they were used to keep servers running but batteries wear out fast adding to the cost. 850VA will allow you to shutdown your rig more orderly Link to comment Share on other sites More sharing options...
LeDoyen Posted June 15, 2021 Share Posted June 15, 2021 All computer PSUs costing more than 2,5$ have active PFC. Since lots of these UPS are used for computer backup, i imagine it shouldn't matter. Link to comment Share on other sites More sharing options...
Corsair Employee jonnyguru Posted June 17, 2021 Corsair Employee Share Posted June 17, 2021 Hello friends! I recently upgraded my computer for work. Installed the Corsair RMx 850W PSU. In our area, the electricity is periodically turned off, so a UPS was required.I have no experience in selecting a UPS, the store manager advised me to take an APC Back-UPS 850VA (~520W) UPS. After connecting the computer, I decided to test the UPS. I turn off the power, and... the computer shuts down. In the APC Windows utility, the total power during operation is shown as 40-100 watts. Googling suggested that my Corsair RMx 850 PSU has an aPFC. Therefore, the UPS must be selected very carefully. Please tell me which UPS is suitable in my case? Thank you very much! Nah. An RMx should work fine with a cheaper standby UPS. Have you tried the "pull the plug while something is on the UPS" test with any other hardware, or just the PC? Link to comment Share on other sites More sharing options...
DoctorIkari Posted June 17, 2021 Author Share Posted June 17, 2021 Nah. An RMx should work fine with a cheaper standby UPS. Have you tried the "pull the plug while something is on the UPS" test with any other hardware, or just the PC? Yes, I tested my old PC. Monitor works too... Link to comment Share on other sites More sharing options...
Corsair Employee jonnyguru Posted June 17, 2021 Corsair Employee Share Posted June 17, 2021 Yes, I tested my old PC. Monitor works too... Weird. So what are you doing, exactly? Running on UPS power and turning the PSU on or is the PC already on and you unplugged the UPS from the wall? Link to comment Share on other sites More sharing options...
DoctorIkari Posted June 21, 2021 Author Share Posted June 21, 2021 Weird. So what are you doing, exactly? Running on UPS power and turning the PSU on or is the PC already on and you unplugged the UPS from the wall? I tested the power outage case: computers and monitors were connected to the UPS, pulled the UPS cord out of the wall, the computer with the Corsair PSU shut down. People suggested that a PSU with aPFC would require a UPS that outputs a pure sine wave. Link to comment Share on other sites More sharing options...
LeDoyen Posted June 21, 2021 Share Posted June 21, 2021 (edited) I tested the power outage case: computers and monitors were connected to the UPS, pulled the UPS cord out of the wall, the computer with the Corsair PSU shut down. People suggested that a PSU with aPFC would require a UPS that outputs a pure sine wave. A bit of googling gave me this : https://www.apc.com/us/en/faqs/FA158939/ TL:DR Active PFC PSUs can create a high current inrush when the UPS switches to battery. (takes up to 8ms they say). This can force the UPS into protection mode They advise to use pure sine wave APCs in your case (page 2, Workstation class or high end gaming PCs) : http://www.apcmedia.com/salestools/RMUZ-7DTKRC/RMUZ-7DTKRC_R1_EN.pdf Since your PSU is 850W, 80+gold, say 1000W tops at the plug, could be a clue. But it's not that the PSU won't stand a Modified sine UPS.. it's the UPS that can't deal with this high power PSU, slight difference. If your old PC uses something close to a 500W PSU, it could explain why the UPS did not shutdown. Edited June 21, 2021 by LeDoyen Link to comment Share on other sites More sharing options...
DoctorIkari Posted June 21, 2021 Author Share Posted June 21, 2021 Since your PSU is 850W, 80+gold, say 1000W tops at the plug, could be a clue. But it's not that the PSU won't stand a Modified sine UPS.. it's the UPS that can't deal with this high power PSU, slight difference. If your old PC uses something close to a 500W PSU, it could explain why the UPS did not shutdown. Well, I'll try to buy a UPS with a double conversion and a pure sine wave at the output in the near time. For example, Ippon Innova G2 1000. I will write about the results later. Link to comment Share on other sites More sharing options...
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