CM GX 550w Causes APC ups to shut down

rakesh12117

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Sep 30, 2011
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Hello Friend's
I have just got CM GX 550w PSu for my GTX 260 backed by APC Back UPS RS 1100. Could not find any other psu available at this point of time. I live in Punjab (India). My problem is when ever the electricity failure occurs, My system shuts down immediately. The UPS gives a continues long beep (probably a sign of overload)after shutting down.what could be the reason ?. The ups has only monitor and cpu connected and ups capacity is 660w.
 
How old are the batteries? The UPS capacity is 660W only if the batteries are good.

A test to determine if the PSU is causing the issue is to disconnect the GTX 260 and power up the PC. Then disconnect the UPS from the wall outlet to simulate a power failure. Does it stay up until the batteries have discharged to the configured percentage?
 

rakesh12117

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Thanks friend for your response . The batteries are two year old. I disconnected the ups from wall outlet at boot manager and it shuts down again. I also have a extremely crappy psu from frontech and with that the ups goes on back up nicely. I have checked this ups on Corsair GS 600w on my friends PC. He runs a gtx 560 on corsair. And the ups worked just fine.
I think , perhaps the gx 550w withdraws more power than mentioned. Also what is this max power output 660w on cm gx 550w ?
 
While it looks like your PSU is defective, it probably isn't. Since the UPS works fine with your friend's PC, you need to verify there isn't a short in your PC that causes the additional power draw. The only way is to test it outside of the case or install another PSU. If another PSU doesn't resolve the issue, then you know something is shorting out.

At boot manager the PSU should draw less than 200 watts because both the GPU and the CPU aren't working hard.

The max power output can be achieved only if all rails are used at 100% and that isn't possible in a PC; you need special test equipment to simulate that condition. At 660W, the UPS would probably shutdown within seconds.
 

rakesh12117

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Very hard to understand that a brand new psu does this. Defective PSU !!!
But it seems to be true.
I had asked the dealer to replace this psu and he agreed. Now I going to have a psu from seasonic ( likely to be S12ii 620w).
I am wondering if seasonic psu, a 17" samsung monitor and a modem can be tolerated by the ups or not !
Last thing you mentioned at full load the ups should shut down within a second. Why ?. It is supposed to give at least 5 to 10 minutes back up at full load.
Thanks for input bro.
 
Even if you had a 3000W PSU, it wouldn't be an issue as long as the system doesn't draw more than what the UPS is rated for. In other words, if the total load at a given time is 400 watts, then it will draw 400 watts * 100 / PSU efficiency. At 80 % efficiency, that would be approximately 500 watts.