I have built, kept and/or sold probably 12 of these z440 and z640 workstations over the past 5 years, and have never seen the memory fan messages pop up until you have more than 4 sticks of memory installed. The 700 watt power supply is more than enough to support 1 32gb stick of ram, so I suspect that, given the two errors that are showing up, that there is something messed up in the motherboard's bios. I would recommend you do two things:
1. reset the bios to factory settings by following the bios reset instructions in the manual (there's a button on the motherboard you press and hold).
2. Do an "bios recovery" following the HP documented procedure that will reload the bios directly from a USB stick with the proper jumper set. The procedure used to be documented here:
https://support.hp.com/us-en/document/c05163478, but I can't find it anywhere on the HP support site anymore, so attached is the relevant text from that document. Make sure the USB stick is formatted fat32, and put the most current bios file in the root of that usb stick.
If this doesn't solve the issue, I suspect there is something wrong that may require a motherboard replacement. They can be found on Ebay for $75 or less.
You could also do a self-test of the power supply -- that is done by unplugging all connectors from the power supply to the motherboard and peripherals, and then plugging in the power supply by itself. If the led light inside the back of the power supply comes on, then it passed the self test. However, I doubt that the power supply is the issue.
I hope this helps,
Philip