Intel P4000 chassis UPS question

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Folsom

New Member
Apr 21, 2016
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I have a dual 2600 motherboard in a P4000 case with a 750W power supply. There is only one PS, the other one is not populated. I have the system powered with a UPS, an APC Back-UPS PRO 1500. Normally the server is drawing around 120W, well under the UPS max draw.

When the power goes out and the P4000 is powered by the UPS the system fans keep ramping up and down and the system clocks down from 3GHz to maybe 300-400MHz. The system is unresponsive due to the low clock speed and hard to power off manually.

Is the P4000 not liking the stepped sine wave from the UPS? Perhaps PFC causing output problems? I see that APC makes a pure sine version of the Back-UPS PRO, would that fix the issue?

Thanks,
Folsom
 

JSchuricht

Active Member
Apr 4, 2011
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It's unusual for a power supply to be that sensitive to a square wave. Double check that there isn't something weird with the UPS communications software doing something while the UPS is on battery. I would love to see the waveform of the UPS to see what it does loaded and unloaded on battery just to make sure it's the UPS and not the PSU failing. Short of you having an oscilloscope, a new UPS might help. Switching to an online/double conversion UPS would replicate the sign wave from the 120V outlet and give the same results all of the time because you are always running off the inverter in the UPS. If you are looking at something like the APC BR1500MS which is line interactive and sign wave, you still have a switchover from utility AC to the inverter AC. If it is a PSU going bad it is possible it would still have issues during the 8-10ms transfer that could destabilize things.
 

RyC

Active Member
Oct 17, 2013
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I have an Eaton 5PX that supposedly outputs a "pure sine wave" and a P4000 + S2600CP + dual 750W hot swap power supply. I get the same fan ramping up and down behavior when it's on UPS power. The instant the UPS switches over to battery, the fans ramp up and down and continue to ramp up and down the entire time while on battery.

The BMC log looks like this:
1569 10/27/2019 19:24:45 PS2 Status Power Supply reports a predictive failure has been detected for the power supply - Deasserted
1568 10/27/2019 19:24:45 PS1 Status Power Supply reports a predictive failure has been detected for the power supply - Deasserted
1567 10/27/2019 19:24:44 PS2 Status Power Supply reports a predictive failure has been detected for the power supply - Asserted
1566 10/27/2019 19:24:44 PS1 Status Power Supply reports a predictive failure has been detected for the power supply - Asserted
1565 10/27/2019 19:24:43 PSU2 Status Power Supply INFORMATIONAL Event:System SmaRT/CLST event, PSU optimization triggered. - Asserted
1564 10/27/2019 19:24:43 PSU1 Status Power Supply INFORMATIONAL Event:System SmaRT/CLST event, PSU optimization triggered. - Asserted
Unfortunately, I'm not seeing the CPU clocking down behavior when on UPS battery. The system seems to continue and respond normally. I'm running ESXi 6.7, but for me, the fans ramping while on battery are an annoying but seemingly harmless side effect.
 

Folsom

New Member
Apr 21, 2016
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I just did a scope capture on the UPS output and I'm not seeing much change when the server is on or off. A little more ringing on the output while the server is on but not much difference.

upswservon.png

I wouldn't mind the sound if the clock didn't downlock to 167MHz, this is on Windows 10.

I get this in the BMC log: "INFORMATIONAL Event:System SmaRT/CLST event, PSU optimization triggered. - Asserted", but not the predicted failure message.

Folsom
 

Folsom

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Apr 21, 2016
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One thing, is it possible to change the downclocking behavior in BIOS? If that is the case then I don't have to upgrade the UPS.

Thanks,
Folsom
 

Folsom

New Member
Apr 21, 2016
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I just received a new APC BR1500MS true sine UPS. When I run the computer from the UPS on battery the system does not downclock. Also the fans don't ramp up and down, they stay the same. There is a brief moment when the fans ramp up but then they ramp back down.

Folsom
 
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