What is reserved debug code 4f?

[Idontworkfornsa]

A newly built system, sometimes when I turned it on, it freezes with bios debug code (onboard) 4f. looking at the manual it says reserved. what does that mean and what could be the reason? if I reset 1-3 times it works fine. could the memory have something to do with it? but why sometimes work sometimes not?

I first encountered this when I added the second memory module (which is part of a set). I first placed it in bank 2. then I got the system freezing at 4f . I switched it to bank 3. the system worked. could be a coincidence though.

my motherboard memory banks marked as following:

bank 4 -------
bank 2 ====
bank 3 -------
bank 1 ====

Currently using bank 3 and 1.

Hardware details:

ga-z87x-ud3h updated to F9 bios
Core i5-4960k (supported from F9 bios)
DDR3 PC3-12800 CFD-W3U1600HQ-4 4gb x 2 (not listed on gigabyte, and I couldn't find motherboard support list on CFD site, amazon recommended them with motherboard lol)

Graphic: ZOTAC GeForce GTX 960 ZTGTX96-2GD5MGS01
PSU: FSP AURUM92+

Also I noticed integrated is not turned off automatically (maybe a feature). and I tried to connect VGA cable beside my graphic card. this causes windows 10 to crash with BSOD if I apply resolution or try to set 3 monitors setting.


Thanks

 

[rar_54]

The only way to find out what the 4f code means is to contact the manufacturer, or perhaps it is listed on their web site. Since your issue is seemingly related to installing the second memory DIMM, try running with only one stick of memory in bank 1. If the issue clears, take out that stick and install the other memory stick in bank 1. Odds are you will find that one of the memory sticks (DIMMs) will not work in bank 1 and that will be the bad memory stick you need to RMA. If you find that both memory sticks work in bank 1 then you need to further explore the motherboard manual to ensure you are using the correct slots and RMA the motherboard if you determine one of the slots is not functioning properly.

 

[Idontworkfornsa]

But the manufacturer Gigabyte manual listed it as reserved. also it doesn't happen all the time. so not sure how to verify the issue if I swap rams.

also I ran memtest86 and found no errors from one pass. does that usually detect ram incompatibility?

Also does anyone know what std in test type of memtest stands for? Standard?