Causes for a PSU to smoke ?

[Zotec_Fury]

Hello. I'm not sure weather this should go here, or in the power supply section.

 

So recently, I got a refurbished hp dl360e gen8 server the whole system was working and booted fine. A week went by (with it working) until yesterday. Late one night while it was rendering a video (cpu around 50%), a thin cloud of smoke that smelt like electrical burn came from where the server is located. I immediately turned the server off by unplugging it from the wall, a little investigation revealed that (I believe) one of the power supplies's (two in the system but one was plugged in) fans burnt out. Removing the PSU from the system revealed that the burn smell came from the fan side of the PSU rather than the connector (the PSU is a 750w model so it would easily be able to power the system). I have contacted the company I purchased the server from and they are sending out a replacement PSU. I just want to know if the server its self had anything to do with the PSU failing, or if it was just a random occurrence. I just want to know if it's safe to use the server with the remaining PSU that wasn't being used. Thanks in advance.

[Windows7ge]

The purpose of redundant PSUs is so when one fails the server can continue to run. You can run the system off the spare PSU but you may get a screeching beep telling you a PSU has failed. There's usually a button to turn off the beeping until the next power cycle.

 

It'd be great to get some photos of the inside of the PSU. It could definitely be the fan itself but see if there's a black stain on the PCB anywhere.

[Zotec_Fury]

3 minutes ago, Windows7ge said:

The purpose of redundant PSUs is so when one fails the server can continue to run. You can run the system off the spare PSU but you may get a screeching beep telling you a PSU has failed. There's usually a button to turn off the beeping until the next power cycle.

 

It'd be great to get some photos of the inside of the PSU. It could definitely be the fan itself but see if there's a black stain on the PCB anywhere.

Yes, I was originally running the server just with one PSU. I haven't taken the PSU apart as I don't really fancy that. There is no physical damage on the out side or connectors.

[Windows7ge]

10 minutes ago, Zotec_Fury said:

Yes, I was originally running the server just with one PSU. I haven't taken the PSU apart as I don't really fancy that. There is no physical damage on the out side or connectors.

If you're not comfortable with it don't worry about it. Being second hand it could be simply age but usually servers are taken off the rack much faster than their usable lifespan is which is why this is such a great market. Server PSU's are usually manufactured to a higher specification than desktop PSUs. Despite this failures do still happen in the enterprise which is why you often see 2+ installed on one server. They're called mini-redundant PSUs. Considering it was under load (though a couple Xeon CPUs alone won't take you anywhere near 750W) it was likely degradation. Plus you don't know if it was dropped and just slapped in the server before it was sent to you. There's a lot of unknowns with retired gear.

 

It is good to hear though that they're sending you a replacement. A lot of places will sell you the equipment as is and if it dies TS.

[Zotec_Fury]

1 minute ago, Windows7ge said:

If you're not comfortable with it don't worry about it. Being second hand it could be simply age but usually servers are taken off the rack much faster than their usable lifespan is which is why this is such a great market. Server PSU's are usually manufactured to a higher specification than desktop PSUs. Despite this failures do still happen in the enterprise which is why you often see 2+ installed on one server. They're called mini-redundant PSUs. Considering it was under load (though a couple Xeon CPUs alone won't take you anywhere near 750W) it was likely degradation. Plus you don't know if it was dropped and just slapped in the server before it was sent to you. There's a lot of unknowns with retired gear.

 

It is good to hear though that they're sending you a replacement. A lot of places will sell you the equipment as is and if it dies TS.

Yeah they are a pretty good company for sending a replacement. So just to clarify it would be totally safe to carry on running the server with the other PSU?

 

The server is running two low power Xeons so the PSU wasn't being stressed. Does something like this (it breaking) happen gradually or does it happen pretty fast because they said they test the systems before shipping them?

[Windows7ge]

Yes. The purpose of the 2 PSUs is in case one fails the server can keep running. With the failed PSU removed the server may beep at you but there's usually a way to turn that off temporarily. Other than that you can run on just the other with no issues.

 

When the replacement shows up you don't even have to shut the server off just pop it in and connect power. They're designed to be hot-swappable.

[Zotec_Fury]

3 minutes ago, Windows7ge said:

Yes. The purpose of the 2 PSUs is in case one fails the server can keep running. With the failed PSU removed the server may beep at you but there's usually a way to turn that off temporarily. Other than that you can run on just the other with no issues.

 

When the replacement shows up you don't even have to shut the server off just pop it in and connect power. They're designed to be hot-swappable.

So what could of caused the power supply to die? A power surge or just one of them things? The server had nothing to do with the PSU dying ? 

[Windows7ge]

3 minutes ago, Zotec_Fury said:

So what could of caused the power supply to die? A power surge or just one of them things? The server had nothing to do with the PSU dying ? 

I went over the possibilities and my own theories two posts up. PSUs fail. The server is second hand. PSUs don't like to be dropped which could have happened. The chances something on the motherboard side causing the PSU to fail isn't high. Usually if something goes over current or shorts to ground the whole system would shut off. For the PSU to smoke and remain powered sounds like a PSU specific failure.

[leadeater]

5 hours ago, Zotec_Fury said:

So what could of caused the power supply to die? A power surge or just one of them things? The server had nothing to do with the PSU dying ? 

PSUs just die with age, some last so long you'll be rid of it before that happens others die sooner. Usually it's electrical/heat stress related to normal operating that weakens components or their connections to the PCB that leads to shorts or arching. Other common one is dust build up combined with moisture/humidity causing a short.

 

The only real downside to running 1 PSU is often that affects the fan speeds of the server and it is much louder. Even with no actual redundancy in power source it's best to plug both in just for quieter operation.