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942-Memory Training error (code 1501)

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Microsoft Windows 10 (64-bit)

I have a z420 from 2016, it's worked without error, all the time. I've played some games over the weekend, I turned it off. Now when I turned it on, a little later in the evening, it made this "beep" and the screen reads 


942-Memory Training Error.

   DIMM 3 on CPU 0 experienced an error during training (CODE 1501).


In the corner it says "F1 : Boot" but when I press the keyboard nothing happens. It doesn't continue from there.

I've tried turning it off and starting it again, but it looks like the error is here to stay.


I've tried connecting a basic HP keyboard as well, and press "esc" and other keys, to try to access the Bios or boot-menu, before the error happens, but it doesn't register any key presses.


I haven't opened the PC because I didn't want to void the warranty, but I guess the computer is so old that the warranty is void anyways? I hope you can help me. I'm willing to buy new RAM or a motherboard or whatever, if it turns out that something's actually broken.


Is it possible that a RAM block can be shaken loose? I have restless leg syndrome, and the desktop is on my desk, so it's quite possible that I might have shaken something over the years... it just feels weird that the error happened while I was away?


I'm afraid I don't know much about the specs of the machine:


6-core Intel Xeon E5-1650@3.20 GHz
Nvidia Geforce GTX 1070 8GB

Please let me know if you need me to find out more. Thank you!


I popped out stick #3 and it complained that there was a problem with stick #1.
I took out stick #1 and it turned on, with 8GB RAM.
I popped them back in, in their respective places and It complained about changed memory layout, when I rebooted it started up without problems and 16GB RAM.
When I ran the Windows 10 memory diagnostic, it finished without finding any problems.


So, I guess it was just craving some attention.

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Since you have not been in your case since 2016 you might find a missing cat's worth of hair or dust in there.  I have an air compressor in our garage at home for such things.  I swear.... I even have resorted to a gas powered leaf blower when I was overly generous in helping a friend.  Put a pencil in the vanes of fans, or hold fingers on them, when you blow the fan's area.  You don't want to over-rev them.  Don't blow on the internal speaker.  You can blow through the power supply if you hold the rear fan from rotating with a thin nonconductive item such as a swizzle stick that can fit through the rear grill.  Once you have things cleaned out you can see the tiny letters printed on the motherboard showing the sequence of memory slots (1->8, and I recall they are listed sequentially right to left starting with slot 1).  This is not related to the order you insert them.... it is just their numbering scheme for identifying them.


So, #3 is easy to find and get to.  I'd pop the stick out and carefully clean both sides of its bottom contacts with high proof isopropyl alcohol.  You can get 90% in larger drug stores.  Try that first, and go from there.  As far as why your keyboard is not working I'd try a new HP PS2 keyboard off eBay rather than a USB keyboard.  The memory cleaning may solve it all if you are lucky.


You also can look carefully at that stick and get the HP part number off it, and the OEM maker such as Samsung, and go search to match that number/maker on eBay.  HP says you just need to match the HP part number but I like to match both.


HERE  is an interesting related post on the forum with an unexpected cause:


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Thank you for the swift reply!

I've updated my question with the solution and accepted your solution.


I don't have a PS/2 keyboard, so I'm not able to access the boot-menu and run a tool like memtest86, for now.


NB: I was actually amazed to find that my computer had next to no dust at all, and literally had a single hair inside it. I've had it on my desk for 3 years, so I guess it doesn't gather much dust up-here 😄


Good suggestion with the pencils in the fans, I've never considered that over-revving them could potentially cause damage.

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