Yes, a flash drive that will boot from a USB port.
On a working computer create a bootable Ubuntu flash drive:
https://ubuntu.com/tutorials/create-a-usb-stick-on-windows#1-overview
Once this flash drive has been made download and install onto this flash drive:
HP diagnostics UEFI version 8.3.0.0:
https://www.hp.com/us-en/campaigns/hpsupportassistant/pc-diags.html
When completed the flash drive will have only Ubuntu and HP diagnostics UEFI.
How old are the RAM modules?
Had they all been in use when the computer was last functioning normally or are they recently replaced RAM?
Make sure that Memtest86+ runs for 8 or more passes.
The more the passes the better the testing environment.
There have been tests where it takes passes into the 20's to find malfunctioning RAM.
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