Z420 Memory Training Error on Startup but I press F1 and it is fine

[GSH6812]

Hi there.

I recently encountered an error when starting up my Z20. There had been no changes made to it at all, it had not been moved and the apps had not changed on the computer. What I did notice the session before the computer did not boot correctly was that the computer was operating very slowly, it was as if it simply had no processing power and everything was super laggy.

The next time I booted up the HDMI monitor would not start up. Or rather it would start up, and I would get  along beep, and then nothing,  The graphics card is on one of the longer two slots in the machine - I cant remember what they are called technically - so I thought I would check to see whether the slot ws corrupted and moved it to other other slot, and rebooted. I got nothing by the same long beep.

I thought I would try to attach a VGA monitor as this doesn't require drivers, and in this case I did start seeing messages on boot and got the following:

Memory Training Error:

Dimm 8 on CPU 0 experienced an error during training (Code 1501).

Reading around I found that this was to do with a possible RAM issue. I

First I removed the RAM on the CPU 0 blokc and re-seated it. The error persisted.

I then did the same again but left the RAM out of the bay completely. 

When starting the computer I got a message telling me that the RAM config had changed, and then told the computer it was okay and it proceeded to boot. I ran windows memory diagnostic on the current configuration and it told me everything was okay.

This is where I am at, at the moment:

The computer starts, hits a long beep for a RAM block that says is problematic, but in fact there is no RAm in that bay, I press F1 and the computer boots normally.

I was reminded doing all this how amazingly built these computers are, HP did such a great job on this Workstation.

Would very much like to resolve this issue I am still having so I can maybe iterate through other testing scenrios and get to a point where the computer simply boots properly. I am now in doubt as to whether the RAM I have removed is actually faulty. I might consider putting that back in and testing whether it boots with F1, but I am sure that this F1 trick will still need to be persisted with even if the RAM is okay.

Thanks