HP Z420 won't boot up after RAM upgrade

[Tateu]

Hello !

So, 4 month ago my PSU (DPS-600UB) died, no more fan spinning and 4 beep and 4 red lights.

I've replaced it by a used one for 30€, plugged in and work like a charm.

Today I got 2 more 8 GB RAM sticks (already have 4 x 8GB = 32GB).

So I switched it off and manage to add them, but when I tried to plug the power supply it boot and shut instantly.

In fact it seems to make the same error code as my previous failure : 4 beep and 4 red lights

But this time, PSU Fan is spinning... So I unplug everything and retry to plug the power cord, green LED at the back, PSU Fan spinning. It's doing this for like 5 sec and turn off...

What you think ? Could be a dead PSU again or the Motherboard could be faulty...

To test the power supply:

1. Unplug the AC power.
2. Remove the power supply.
3. Plug in AC power and verify the following:
   • If the green BIST LED on the rear of the workstation is illuminated and the fan is spinning, the power supply is functional.
   • If the green BIST LED is not illuminated or the fan is not spinning, replace the power supply.

 What i've find:

Thanks for all the advices !

Matthieu

[SDH]

I'd first suspect mismatched memory. Can you take out the 2 new ones and try booting again?

If you bought used HP memory with the same assembly part number on the HP label (on the right side of the memory stick on a label) then the chances of that is lower.

If it is not HP memory with the same part number on the HP label then the chance of mismatch is much higher. For example, if the rank (single vs dual rank) is different and the memory is mixed in the same channel with another rank then that is a common/guaranteed source of boot failure.

[Tateu]

I've already tried to place them exactly as they were before but the result is still the same.

They came with the workstation, and were in place since i've received it.

I've even tried to place only two of them without sucess. 

But so you know the two 8GB I'm trying to had are bit different but should't cause any issues. In fact mine are PC3 and the two's I wan't ti add are PC3L which mean Low consuption. Docs Said that the motherboard should take them at 1.5v without problem 🤔

I've see sometjing else, my PSU, when everythings unpluged, start, fan turn on, light too but only for like 4 sec. And i've find someone that sell one for 30€ and he have been able to take a picture of his PSU ( without anything else plugged in) with the fan and led ON and they stay like so...

Hope my explanations are clear enought 😅

So to respond to your answer, even with the Last working config it won't boot up.

(i've done a CMOS replacement since i've published here but nothing have changed)

Thanks SDH I truly appreciate your involve 👍

[SDH]

Well, it sounds like a replacement power supply is a reasonable next step. I personally don't mix memory including L and non-L.

I stick with ECC buffered and HP part label as much as possible. Maybe it is time to look at getting a Z440?

[DGroves]

in general,...............LOW POWER MEMORY should not be mixed with standard ram

on many systems the memory controller is unable to work/cope with the different voltages (1.5 and 1.35 at the same time)

 while the low power dimms will work HP only supported the std 1.5v dimms

per HP

1.35V and 1.5V DIMMs are supported, but the system will operate the DIMMs, safely, at 1.5V only.

in other words the z420 will ignore the 1.35 and instead use 1.5v

most low power dimms are dual voltage, but some are not or are unstable when used at 1.5v 

https://h20331.www2.hp.com/hpsub/downloads/z420_memory_configurations.pdf

also many people confuse "Load Reduced" Dimms with low power dimms in regards to dimm naming

Load reduced DIMM is designed with a buffer chip (or chips) to replace the register to help minimize loading and these dimms are not compatible with normal dimms, also LR type dimms are only found in large capacity mem modules greater than 16gb in size

[Tateu]

@SDH

I've ordered one and will change it asap.

But I've a nice surprise at morning, Z420 boot up normally...

I can now turn on/off without issues... I've added the 16GB RAM too without issue... 

But instead of doing : 8 - 8 - 8 - 0 - CPU - 0 - 8 - 8 - 8

I did : 8 - 4 - 8 - 4 - CPU - 4 - 8 - 4 - 8

Because that was the Best suggested in the docs.

So I can say that it's fine for now, I may actualize this topic if PSU fail again (to comment about PSU replacement).

Thanks for your help !

Appreciate !

Matthieu

[Tateu]

@DGroves

Yes I get it but it's not a corporate infra so as far as it "works", i'm ok 😉

So you know I've got a nice surprise at morning, Z420 boot up normally...

I can now turn on/off without issues... I've added the 16GB RAM too without issue... 

But instead of doing : 8 - 8 - 8 - 0 - CPU - 0 - 8 - 8 - 8

I did : 8 - 4 - 8 - 4 - CPU - 4 - 8 - 4 - 8

Because that was the Best suggested in the docs you've sent.

Show 48GB at 1333Mhz so should be ok !

So I can say that it's fine for now, I may actualize this topic if PSU fail again (to comment about PSU replacement).

Thanks for your help !

Appreciate !

Matthieu