Can I use riser without CPU installed Z 620

[WhoduVoodoo]

I purchased my Z 620 with riser that had memory installed but I only had a single CPU.

Later I purchased a pair of CPU but the unit didnt recognize the 2nd CPU.

I had to purchase windows 10 pro for the second CPU to show up.

I have now gone back to a single CPU but a more powerful one.

If i try to use the riser I get errors and the machine wont start.
I'm trying to use 4 x 16GB so that i have 64GB  but when I install all 4 on the lower board the info only shows 32GB ?

Thanks for any help

[SDH]

No, you cannot use the riser or its memory if there is no processor in it.  You have discovered that the correct memory, the correct riser, and the correct processors present are important. The questions below are meant to be educational, not demeaning, and to educate quickly.

Were you using the latest BIOS?  Some later processors will not be recognized by the system if they are not running under the latest BIOS.  Makes sense... that is how new processors are are added to the certified white list by HP.

What processor(s) were you trying?  Some processors won't work on older versions of the Z620 motherboard..  There is a version 1 and a version 2 with different boot block dates which is easily seen from inside BIOS.  Trying to run version 2 processors on the version 1 motherboard won't work properly...  makes sense...

What processors were you trying?  Some processors can only work in a single-processor build.  Trying to run two processors at the same time in a dual processor build won't work if they were not designed by Intel to be able to run as a dual processor build.  Makes sense....

What processors were you trying?  What version of the motherboard were you trying?  If the processor is not certified by HP as being for the type of HP motherboard you have they generally won't work.  Again, makes sense...  One might think they should work, and even if logically they should work that does not mean they will.  HP has a white list and if the processor is not certified in that list it generally will be black listed.  There are a few rare exceptions.

Our  Z620 risers here all work fine.  We however generally run on single processor builds as detailed here by Bambi and Brian, with some overclocking thereby.  For our needs the risers are generally not worth the hassle, but for others they can be a valuable boost in cores and memory load.  We only run v2 workstations for the ZX20 generation workstations.  If there is a v1 box found I convert that to v2 with an eBay proper motherboard transplant.

[WhoduVoodoo]

My single processor is E5- 2697v2 2.7GHz 12 core and is working fine.

The only issue I had was trying to keep the 2nd riser as it had extra ram.

This lead to a different problem as I then purchased 4 x 16GB of ram but once installed  the modules are registering as only as 8 GB.

[WhoduVoodoo]

I was following the solution in the post and believe I was doing the same thing ?

https://h30434.www3.hp.com/t5/Business-PCs-Workstations-and-Point-of-Sale-Systems/Will-16GB-RAM-work...

What are we doing different ?