RAM upgrade rejection

[JakeGu]

Hello, everyone!

I recently bought two 8GB DDR4 2666 sticks online and even though I have a lot of experience with upgrading/replacing/overclocking RAM on desktops, I've encountered an issue on my laptop.

The thing is, the laptop won't boot if I put both of the new sticks into both RAM slots -> the screen gets heavily glitchy( a ton of horizontal "glitch" lines appear ) after the HP/Windows initial Loading screen and I have no choice but to forcefully shut the laptop down.

The funny thing is that the BIOS fully recognize the sticks as a 2x8GB combo and even the tests I ran with the Intel Testing pre-boot option said the RAM sticks fully passed.

I've always seen people say not to mix two different ram sticks so I was bewildered by the fact that two of the same sticks( which should genuinely be compatible ) don't let the device boot. Thinking maybe Windows 10 was flipping me off, I tried booting Linux up, only to encounter the same issue(  "glitched-up screen" ).

In the end, I decided to try using the default 8GB stick in one slot, and put one of the new sticks into the second slot( and exchanged both of them, thinking maybe one was broken; but both worked fine if used one at a time ).
To my surprise, this combination worked. The laptop booted up, I had 16GB of RAM and it was actually running in dual channel.
However, the second stick, at least by the specs and reviews/CPU-Z screenshots other posted, is a CL16 one, yet the default/stock stick seems to be CL19, thus forcing the second/new one to go CL19( at least I came to that conclusion since CPU-Z shows CL19 in the Memory Info tab ).

Logically, I was still frustrated, because two different sticks should've been the combo to glitch out, at least in my opinion, and the old one seems to be holding the new one down.

So I did some googling, only to find out there can be a new RAM rejection because of the CMOS battery.

Dell laptops seem to have an option to hold the power button for over 10 seconds for it to reset but HP doesn't even mention the CMOS battery in a single manual online.

It's also worth mentioning I did stumble into the CMOS reset pre-boot screen several times and I did let it get reset( the menu did say it was going to get reset ), but that didn't help.

Long story short:
Why does my laptop reject two of the same sticks if they're used at the same time but a combo of the default 8gb stick and one of the new 8GB sticks works without a single hiccup?

*I've attached the picture of the display glitch, one pic of the working combo(old+new stick) and the CPU-Z pic*

Cheers.

[Riddle_Decipher]

@JakeGu Welcome to HP Community!

I went through the details and looks like this device only supports memory in the below format:

● 8 GB (8 GB × 1 or 4 GB × 2)

● 4 GB (4 GB × 1)

For more details: Visit page. 41, 42 & 43 of Chapter 5 Removal and replacement procedures for authorized service provi...

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[Huffer · Accepted solution]

I have posted this countless times but here it is again. HP laptops are not made to work with high performance "gaming" type memory with aggressive timings and latency. You say the original memory was CL = 19. You installed CL = 16 thinking somehow you were going to speed up the laptop. Instead the system became unstable. When you mixed the modules the CL = 19 forced the other stick to run at the less aggressive settings but the motherboard will not do this by itself. The CMOS battery has nothing to do with it. Stick with standard OEM memory and you will not have this issue. 

[JakeGu]

Thank you for the answer.

CL19 SODIMM ram( thus inferior ) seems to be rare in my country and there is only one manufacturer whose price is unrealistic.

The RAM I purchased wasn't screaming "professional" or "gamer", I merely looked for RAM with the lowest price and best rating.

And honestly, I couldn't find the manual for my specific variant and I figured the laptop itself could force the sticks into " obedience", since some mentioned their laptops underclocked the mentioned sticks to 2133MHz( I simply forgot about CL values, as I never had issues with that aspect of RAM ).

Thank you for the answer nonetheless, I guess I will stick to the mentioned and functional combination ( as one CL19 8GB stick here costs 68$ while I paid 52$ for two CL16 8GB sticks ).