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Universal Power Supply causing startup issues

S

sabester24

macrumors member
Original poster
Jan 30, 2013
49
0
I have a late 2015 5K iMac plugged into a CyberPower 850PFCLCD. My iMac kept freezing during startup- the loading bar would get stuck about half way. After doing some typical trouble shooting (i.e. PRAM and SMC reset) without any success, I started unplugging USB connections to try and isolate the problem. Turns out, when I unplugged the CyberPower UPS USB cord, the startup freezing went away. The usb connection between the iMac and UPS allows me to mange settings in case of a power disruption/outage, so it's a fairly important USB connection.

Anybody else experiencing something similar with a UPS? Any other ideas that would allow me to have the UPS plugged in via USB and still allow the iMac to startup properly?
 
Maybe the startup load for the iMac exceeds to specifications for the UPS?
 
BrianBaughn said:
Are you using the Mac's built-in UPS management?
Click to expand...

I believe I can only do this if I have the iMac plugged into the UPS via a USB cord- hence my problem...
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maflynn said:
Maybe the startup load for the iMac exceeds to specifications for the UPS?
Click to expand...

Can you elaborate? I've had the UPS for about 2 years and haven't had any issues until recently. This is only a problem with the USB compatibility. Having the UPS's USB cord plugged in to the iMac is what is causing issues. The iMac seems to run fine with the power cord connected to the UPS.
 
sabester24 said:
I've had the UPS for about 2 years and haven't had any issues until recently.
Click to expand...
Well if its not a new UPS with new issues, then my thinking is incorrect. If it was fine, at some point and now its having issues, perhaps the UPS is failing in some way.
 
So after doing some more digging and research, apparently this had to do with needing to install startup daemons. I was able to download software from the manufacturer of the UPS and now the issue seems to be resolved.
 
sabester24 said:
I have a late 2015 5K iMac plugged into a CyberPower 850PFCLCD. My iMac kept freezing during startup- the loading bar would get stuck about half way. After doing some typical trouble shooting (i.e. PRAM and SMC reset) without any success, I started unplugging USB connections to try and isolate the problem. Turns out, when I unplugged the CyberPower UPS USB cord, the startup freezing went away. The usb connection between the iMac and UPS allows me to mange settings in case of a power disruption/outage, so it's a fairly important USB connection.

Anybody else experiencing something similar with a UPS? Any other ideas that would allow me to have the UPS plugged in via USB and still allow the iMac to startup properly?
Click to expand...

I have the same issue - both with a Cyberpower UPS and an APC UPS.
You should NOT have to install software for OS X to boot normally with a UPS attached. I've used both without problems for years.

This is a bug in 10.11. I've filed a bug report with Apple.
Apparently they rewrote the USB stack for 10.11 and there's a lot of bugs.
 
I had the same issue and my work around was not to plug the ups into the ports on the back of the mac, but to use a USB hub instead. This allows my iMac to boot without any issue and still have information about the battery. Now my APC RS ups don't properly come up with all the unit name and all that jazz but it will see the % of battery and can do its own shutdown if the % dropb below a certain point
 
roadkill401 said:
I had the same issue and my work around was not to plug the ups into the ports on the back of the mac, but to use a USB hub instead. This allows my iMac to boot without any issue and still have information about the battery. Now my APC RS ups don't properly come up with all the unit name and all that jazz but it will see the % of battery and can do its own shutdown if the % dropb below a certain point
Click to expand...

I tried that. Even plugged into a hub I get boot failures (though less often).
Hopefully it'll be fixed in 10.11.3
 
mihirkamat said:
I have the same issue - both with a Cyberpower UPS and an APC UPS.
You should NOT have to install software for OS X to boot normally with a UPS attached. I've used both without problems for years.

This is a bug in 10.11. I've filed a bug report with Apple.
Apparently they rewrote the USB stack for 10.11 and there's a lot of bugs.
Click to expand...

While that may be true, downloading the startup daemon did fix my problem. Also just to clarify, it's not that I had a UPS attached from the power cord- it was the usb connection between the UPS and iMac that was causing the issues.
 
iMac power supply is no as same as PC, it used sb 12v replacement the normal 5v at PC. and also, its SMC has connection with power supply when you plug the power cord in.

I wan't recommend the way that you were using UPS.
 
derickz said:
iMac power supply is no as same as PC, it used sb 12v replacement the normal 5v at PC. and also, its SMC has connection with power supply when you plug the power cord in.

I wan't recommend the way that you were using UPS.
Click to expand...

Do you mind elaborating? I'm a bit confused. Are you saying you don't recommend me using the UPS with my iMac?
 
sabester24 said:
Do you mind elaborating? I'm a bit confused. Are you saying you don't recommend me using the UPS with my iMac?
Click to expand...

They are difference, you can using the UPS to supply the 110v power, but I won't using their power management.
 
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