HP Z420 white ram slots don't work standalone?

[Smonke]

So I bought this HP Z420 for about $110, without ram, thinking I was able to use my 4x4gb non ecc ddr3 sticks, none of them worked on this system. so I assumed that the HP z420 doesnt support non ecc ddr3 modules, please confirm if you know for sure

 

right after I realized that, I switched to my only 8gb registered ecc ddr3 module, though HP claims that registered ECC sticks wont work, it did. but only on the black slots, when populating the white slots standalone, the power button and motherboard flashes red lights and it beeps 5 short beeps, memory error. The manual does state that the slots must be populated in order, but I was able to populate it out of order with the black slots

If anyone has had experience with HP Z4xx systems, please confirm!
 

z420_memory_configurations.pdf

[Aragorn-]

The manual you linked specifically says to load the black slots first. Each memory channel has one black and one white slot.

 

Memory support on workstations like this can be weird. Mostly because they only test and verify the class of memory they intend to sell with the machine, in this case, ECC unbuffered.

 

The CPU/chipset supports the other types, so you get weird quirks that some things will work and some work. The Dell equivalent machine (T3610) with the same chipset will run everything from stanadard unbuffered dimms thru ECC registered dimms.

[Smonke]

1 hour ago, Aragorn- said:

The manual you linked specifically says to load the black slots first. Each memory channel has one black and one white slot.

 

Memory support on workstations like this can be weird. Mostly because they only test and verify the class of memory they intend to sell with the machine, in this case, ECC unbuffered.

 

The CPU/chipset supports the other types, so you get weird quirks that some things will work and some work. The Dell equivalent machine (T3610) with the same chipset will run everything from stanadard unbuffered dimms thru ECC registered dimms.

so since each white ans black slot represents one channel, what do you think the chances of me getting one with only 4 functioning ram slots but with all 4 channels working?
I've also been getting this error code on every boot, OCCT doesnt seem to think that there're any problems with my ram when I did a test. I'm very confused
Solved: 942-Memory Training error (code 3016) - HP Support Community - 5847857

[Aragorn-]

I think all you can do is source approved ram for it, with anything else your in flip-a-coin territory.