HP Z620 Workstation - one memory slot problematic

Spray the slot with contact cleaner directly in the slot, spray well around that area and spray on the back where the solder joints are.
You may as well clean the whole board while you are at it so spray that stuff all over the board you will need a few cans and just go thorough with it. Spray the ram that has been in that slot too.

it could also be a short circuit so test the board on something non conductive.

if it does not come back after that then its faulty.

How many CPU do you have?

From https://h20331.www2.hp.com/hpsub/dow...igurations.pdf

Supported Memory Modules1
The types of memory supported on a HP Z620 are:
• 2 GB and 4 GB PC3-12800E 1600MHz DDR3 Unbuffered ECC DIMMs
• 4 GB and 8 GB PC3-12800R 1600MHz DDR3 Registered DIMMs
• 1.35V and 1.5V DIMMs are supported, but the system will operate the DIMMs at 1.5V only.
• 2 Gb and 4 Gb based DIMMs are supported.
See the Memory Technology White Paper for additional technical information

For 16G you should use 4x4 G on slots 1, 3, 6, 8
16G memory modules are NOT recommended
For 64 G you should use 8x8G on slots 1, 2, 3, 4, 5, 6, 7, 8

its a quad channel platform over 8 slots where it can support 256gb of ram and upwards
This means to hit 256 then you need 32gb sticks at least.

The denotation of capacity per stick won't mean its causing an issue 16gb sticks are within normal.

These boards are notorious for ram slots dying. Especially OEM ones because they use weaker parts.

I know the spec sheet says what it says but this is a lie its always been the case with HP they under spec the support requirements for some reason.

Ram is denoted buy the CPU.

The other factor is that the docs say up to 96gb which is a strange amount you won't get that over 8 slots without 16gb sticks.
the last point is that if 16gb in one stick where not acceptable then all the ram would fail not just one stick/slot.

The ram controller is on the CPU and is what dictates the ram capacity. These CPU can start off at 256gb and go higher on better models.

lse123 said:

HP UEFI Hardware diagnostics app
This is in BIOS/UEFI
?
Or, needed to get installed?
Or, check ✔️ if is installed, and if not then, install it...?

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Can you provide any video url on this from hp or YouTube?

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If faulty 3 slot black,
Can I use another slot from 2, 4,... the white slots?

Running those tools is done from a usb at boot so you boot the usb instead of your main hard drive.
I don't think it is warranted that memory test will be testing registered memory so it won't tell you anything significant. Because the computer is not picking up that slot which means not registered from that slot.

The problem is that slot 3 is not registering that ram stick. its either faulty or has bad conductance and you need to clean it.

The fact also that you tried small denominations within "spec" under 8gb in that slot even though this does not matter but it is displaying the same outcome.

I would assume that the slot is defective its common on quad channel platforms and is one of the reasons its not common today.