Z170 Pro Gaming DIMM_A2 not working

[Gehirnkrampf]

Hi Forum!
i've build myself a new PC but now i have a problem i could not solve...


- Asus Z170 Pro Gaming Aura
- Intel Core i5 7600K (Kaby Lake)
- Gskill Ripjaws V 2 x 8 GB with 3000 mhz

Latest Bios update is installed!


Problem is:

- when i put one single ram chip into the DIMM_A2 slot (according to the manual) i get the red DIMM led and the pc wont POST.
- the only slot which works is DIMM_B2.
- when i put one chip into B2 and the other in B1, it shows 16GB in the bios, but in windows it only shows 8 GB. i am ok with that, since B1+B2 is not the correct placement

thing is, A2 does not work.

- i tried to up the Voltage from 1.2x V to 1.35V the Ram is supposed to run at but no difference.
- looked at the slots and the dimms, no mechanical damage visible there.



could this be a incompability with the kaby lake processor and the Z170 mainboard, although the newest Bios version is updated?

i mean, it is strange that the ram chip won't work on A2, but on B2 it does (with 2133 mhz and not 3000 mhz even though i set it to 3000mhz)


mainboard defective?
ram defective?
user stupid?

[Nate152]

Gehirnkrampf

Welcome to the ROG forum.

Is your ram kit a single 16GB kit or two sticks purchased separately?

Try with one stick in slot B2, boot into the bios and raise the cpu system agent voltage to 1.15v - 1.20v, set the cpu vccio voltage to 1.15v. F10 and Enter to save and exit, boot to windows then shut down your pc and install the other stick in slot A2.

Start your pc , does it boot to windows with both sticks?

[Gehirnkrampf]

Nate152 wrote:
Gehirnkrampf

Welcome to the ROG forum.

Is your ram kit a single 16GB kit or two sticks purchased separately?

Try with one stick in slot B2, boot into the bios and raise the cpu system agent voltage to 1.15v - 1.20v, set the cpu vccio voltage to 1.15v. F10 and Enter to save and exit, boot to windows then shut down your pc and install the other stick in slot A2.

Start your pc , does it boot to windows with both sticks?

Hi Nate and thank you for your advice!

it's 2 x 8 GB:
Gskill F4-3000C15D-16GVGB Memory D4 3000 16GB C15 RipV K2 2x 8GB, 1,35V


i did as you told me. but when booting with those settings (i took the lowest, ie cpu system agent voltage 1.15v and vccio 1.15v) it did not boot at all. when i then went to those settings, it was showing in red so i went down in 0.05v steps down to like 1.05v (default settings were like 0.95v) when it booted fine and well.
i then installed the second stick into A2 and it did not boot. next i took the stick out again and on the next boot it said "overclocking failed" but everything went fine afterwards (still with just one stick).

i played a little with XMP and manually setting the ram voltage but nothing seemed to help.

my next plan would be to change my i5 7600K to a fallback Celeron G3900 to a) see if there is different behaviour and b) if there are bent pins on my i5.

[Nate152]

Yes, bent cpu socket pins can cause the ram slots to not work, that would be the next thing to check.