Cisco Warns UCS Chassis Power Supply Could Drop • The Register

Cisco has warned owners of its UCS servers that they may have a loose screw. In the UCS X9508 chassis that houses their servers, ie.

A field notice issued by the company states: “The power entry module (PEM) of a small number of UCS 9508 units may not be fixed in the chassis and may be removed when the power cord is disconnected from the frame.

“The captive screws designed to secure the PEM were not properly tightened and some chassis were shipped with the module improperly attached.”

If you’re the unlucky owner of one of these chassis, Cisco warns that the PEM “could slip out of the chassis when the power cord is removed.”


Cisco has offered a workaround, and for once you don’t need to download and apply a patch. Instead, you will need a screwdriver. But not just any old screwdriver, because this job requires a T10 torx head screwdriver.

Cisco’s instructions, pictured below, suggest that a power screwdriver can do the job if you can “tighten to 4.5-6 inches”, and leave hand-tightening as another option.

Just screw it on. Click to enlarge

Don’t try any of this until you have shut down all the servers in the chassis, as well as the chassis itself. It’s best to do this from the rack’s PDU, because the PEM could fall out if you try to disconnect at that end.

Cisco’s field advisory states that only “a small number” of chassis have a loose screw. Nevertheless, the issue is a bit embarrassing because the UCS X9508 is Cisco’s newest chassis and was only released a few months ago to house its X-series servers which can be used to deploy resources from storage, CPU and GPU. The chassis has eight forward-facing server slots that can hold what Cisco describes as “a pool of future I/O resources that can include GPU accelerators, disk storage, and nonvolatile memory.”

Hopefully Cisco tightens the screws properly on these future devices. ®

Alan A. Seibert