Question B channel of DRAM

Mar 26, 2020
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Running Z390 AORUS ULTRA with initially KHX3200C16D4/8GX (a kit including 2 x 8GB running in Slots B1 and B2) in XMP mode @ 3200mhz/1.35v.

I would occasionally see POST fail and need to reset BIOS, from there I could boot without XMP active and restart the PC to enable XMP mode @ 3200mhz again. I could live with this, as frustrating as it was at the time

I purchased a second kit of the same 2 x 8GB RAM (1st set manufacture week 12 of 2019, 2nd set week 51 of 2019) and would experience the same issue from time to time.

Today, booted and couldn't POST at all before seeing a memory error in the BIOS stating: you are running RAM in A1 and A2.. change to A2 and B2 to boot. Strange, I have 4 sticks of RAM installed. Ram in B1 and B2 was not detected at all.

Proceeded to debug the RAM, removing paired sets at a time and testing them.

Turns out as follows:
  • RAM in A1 registers as 8GB (week 51 of 2019 kit)
  • RAM in A2 registers as 8GB (week 12 of 2019 kit)\
  • RAM in B1 registers as 1GB (week 51 of 2019 kit)
  • RAM in B2 registers as 1GB (week 12 of 2019 kit)
The RAM in B-slots isn't detected by Windows @ 1GB, it can't be seen when selecting the respective slot # in CPU-Z.

It looks like my motherboard has just fried two sticks of RAM. Not sure if there's something more to try to do and/or test further to the above.

Or RMA on the mainboard?

Cheers
 
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update the BIOS within BIOS (not Windows!)

Does it work without the XMP profile enabled?

check each stick in A2 with memtest.org usb autoinstaller (bootable USB flash drive)

Does the newer sticks work correctly without the older ones?

Check the CPU socket of the motherboard for bent or discolored pins

which CPU are you using?
 
Mar 26, 2020
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Thanks helpstar and Calvin7!

It appears confirmed, one of the new 8GB sticks (operating previously in B1) and one of the old 8GB sticks (operating previously in B2) are dead.
The partnered stick in each of these two separately purchased kits is functioning OK in combination, in A1/B1 and also in A2/B2 DIMMS both. I am concerned - given that two sticks have fried in B1 + B2 yesterday, that running one of the two remaining RAM sticks in the B channel will lead the mobo to fry this someday soon too.

See below, feel welcome to ask any questions


helpstar:
update the BIOS within BIOS (not Windows!)
Already running F10b - latest

Does it work without the XMP profile enabled?
Computer does not boot when either 1x RAM stick (or 2x RAM sticks) I listed as appearing now as “1GB” in BIOS above are inserted into the PC. Only boots when the 2 x correctly registering 8GB sticks are installed (maximum) and with these two functioning sticks, XMP works.

check each stick in A2 with memtest.org usb autoinstaller (bootable USB flash drive)
These two sticks allow me to boot, POST and run memtest successfully:
-RAM in A1 registers as 8GB (week 51 of 2019 kit)
-RAM in A2 registers as 8GB (week 12 of 2019 kit)

These two sticks don’t allow the PC to boot or POST. Boot loops, with DRAM LED on mobo highlighted, C1 on BIOS
-RAM in B1 registers as 1GB (week 51 of 2019 kit)
-RAM in B2 registers as 1GB (week 12 of 2019 kit)

Does the newer sticks work correctly without the older ones?
No, only one old stick and one new stick work. One of the newer sticks (originally in A1) and one of the older sticks (originally in A2) are functioning ok – register as 8GB sticks in BIOS.

The other new stick (originally in B1) and other old stick (originally in B2) appear as “1GB” in the BIOS – and do not appear in in Windows/CPU-Z.

Note: I can only boot if I use one of the functioning sticks alongside a non-functioning stick. Windows with this shows 8GB total ram in this case for the two sticks, and CPU-Z does not identify the stick showing as “1GB” in the BIOS.

Check the CPU socket of the motherboard for bent or discolored pins
CPU socket is perfect. Computer was also working OK with 4 x sticks of 8GB ram for 3 months until yesterday. Computer appears to have fried one new and one old RAM stick which were running in B1 and B2 respectively.

which CPU are you using?

I9-9900k


Calvin7:
Those type of memory combinations have no guarantee to be compatible together. If the PC boots up, there are no guarantees as to how it will run.
Please elaborate on ‘those types’? Do you mean two pairs of the exact same model of RAM, purchased/manufactured separately?
I.e. 2 x 8GB sticks manufactured week 12 of 2019 + 2 x 8GB sticks manufactured week 51 of 2019

Memory not being detected is often caused by damage to pins in CPU socket after faulty CPU installation.
CPU + AIO installed 11 months ago, untouched since.
The first 2 x 8GB booted and for 6 months (with intermittent boot failure which required resetting BIOS and enabling XMP again). Installed 2 x 8GB more sticks, ran for 3 months until yesterday (again with intermittent boot failure which required resetting the BIOS and enabling XMP again).

The two sticks at today which are registering still as 8GB (one old, one new stick) can be booted in DIMM’s A1/B1 combo and A2/B2 combo.
 
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