Laptop won't start after reboot when installed new RAM

[Tony_Kov]

Dear Diaro561,

I still think that the HP BIOS operates in the following way with relation to installed RAM:

1) it boots with the stored settings of RAM timing;

2) then it checks the maximal-minimum timing values (i.e., if there are two modules, one with CL 14/15/16 and the other with CL 17/18, it will select CL 17) supported by the installed RAM modules (from JEDEC or XMP, who knows);

3) if this timing settings are not the same as the stored in the BIOS memory, it rewrites them.

So, the next time the system boots, it takes the new settings, and if the timing is too low to operate, it fails to boot.

This idea is supported by the fact that I was able to successfully operate the laptop with officially supported 16 GB RAM memory replacement by Kingston (or original 8 GB RAM), and that HyperX  module.

Alternatively, it may appear that this laptop does not support XMP profiles at all, and only supports JEDEC, so if it does not find a suitable JEDEC table from any module installed to get the right settings, it fails.

P.S. Glad, that someone still finds this topic useful.

[diaro561]

Thank you very much for this profound explanation. That in fact was what I was looking for. 
I just wanted to understand this. Still need to find out what the CL of these HyperX modules are... and your reply let me think it could work if I put the original 4GB in Bank1 and one 16GB HyperX in Bank2? - need checking this out.
If it works, then fine, if not ... then (now) fine too.

[Tony_Kov]

Just, please, keep the thread updated if you succeed or not. I think it will be useful for the other people as well.

[Eugen3]

Same situation here. Bought a 840 G5 with a single stick of 16GB ram from the factory.

Bought a HYPERX impact 2x16GB kit for it. (2400MHZ, CL14). 

Boots at first. Error codes at the next restart. 

If HP added the option to at least select one of the lower performing performance profiles for this ram there would be no problems at all.  But it goes to CL14 which is not allowed by the elitebook bios and he doesn't want to boot the next time you restart it. 

I tricked the problem instead of selling the ram.

When i combine the HyperX ram with the default 16GB stick. He automatically chooses a performance preset that both sticks can work with. In this case that seems to be CL15 @ 2133mhz.  And then the machine works flawless. 

I checked, dual channel is functioning well to. This is better then having to sell the new HyperX ram but there is still no reason for such bad BIOS decisions. If the motherboard can't work with CL14 ram then at least just rise the timing to CL17 and everyone is happy. Any ram stick which is stable at cl14 is going to be stable at a higher timing value. Only the other way around wouldn't be true. 

[Nick1521]

Same issue with my Elitebook 840 G4 and HyperX 16GBx2 kit (DDR4 - 2400 CL14)...premium laptop that time, I tried to choose premium RAM but...nice boot at first (top performances using it!), error beeps at next restart (3 long, 2 short).

Thanks Tony_Kov for your explanation.

Has anyone solved this issue? Considering that at first boot everything is great (!) is there any possibility to fix it, keeping the HyperX kit mounted?

Thanks everybody.

[diaro561]

There seems no other solution than obtaining HP certified memory bricks. These HyperX I used were confirmed by Kensington for not being compatible with HP 840s. They then pointed me to their product that would have worked. Guess what: much more expensive, so I decided to reduce to 2x 8GB ... since then my notebook is happy and me too. Also see feedback Tony_Kov, Posted  ‎on 06-05-2019 02:36 AM - edited ‎06-05-2019 02:41 AM .

[alanwake19]

Same issue here with Probook 450 G5, support page says that tha lapttop supports up to 32GB of memory but it never says that there is a minimum CL supported, this is a bad move from HP.

[Nick1521]

I agree with you Alan, I think a software patch (BIOS) should be enough to fix the CL problem.

Anyway, I have now replaced my HyperX modules with 2 Crucial Ballistix 2666 MHz, DDR4, 32 GB kit (16 GB x 2). CL16.

And everything goes fine.

[Moravista]

Same problem here on a Probook 450 G5. I have now ordered the Patriot VIPER Steel 16GB DDR4 2400 SO-DIMM which use CL15 - I will keep you updated whether this works. The problem with the HyperX modules is disappointing though!

[Moravista]

Update: my Probook 450 G5 is now running at CL15 with one Patriot Viper Steel module and one HyperX. My amateur conclusion is that CL14 is too fast, but the machine will happily run at CL15. I hope this will help some of you to buy the right RAM when upgrading. CL15 seems to be the fastest that will run without problems.