HP840 G4 memory (RAM) upgrade to 32G

[CMaxY]

I have some problem.

HP840G3 2x Samsung 8G memory work fine.

core i5-7200U 2500Ghz

Samsung M471A1K43CB1-CRC (PC4-19200 2400MHz CL17 1.2V Bulk) 

Samsung M471A1K43BB1-CRC (PC4-19200 2400MHz CL17 1.2V Bulk)

two different modules, but it's work perfect = DUAL mode at 2133Mhz 

In user manual "Max memory size 32G", ok.

But it dosn't work with Kingston HyperX Impact 2x16 modules

first try - Kingston HyperX Impact [HX426S15IB2K2/32] 32 G -  2666Mhz CL15

second - Kingston HyperX Impact [HX424S14IBK2/32] 32 G - 2400Mhz CL14

No BIOS boot, black screen, only beep and num flashing.

BUT!!! if i mix one old and one new modules, it's work!!!

Samsung 8G + Kingston 16G at 2133Mhz

Kingston 16G + Samsung 8G at 2133Mhz

ok. let's try Kingston 16G 2666Mhz + Kingston 16G 2400Gz

No!!! dosn't work!!! 

Why?

[Huffer · Accepted solution]

Because the memory you are trying to install is not compatible. It wants DDR4-2133 or DDR4-2400 at standard OEM latency likely CL = 16. Not 2666 not Hyperx low-latency gaming memory. 

[CMaxY]

Ok. Thanks.

BUT....

if i mix modules it's work. Norm and fast modules work together. 

it's mean that motherboard CAN work with this memory....

[Huffer]

Yes the presence of the compatible module forces the other to the right timings. But the fast module will not work by itself. 

[CMaxY]

Thank you, again 🙂

One more question: a you sure?  DDR4-2400 CL16  will be Ok?

[Huffer]

About as sure as I can be. 

[CMaxY]

Thanks.

You are right.

BLS16G4S240FSD.16FBD

Ballistix Sport LT 2x16GB

DDR4-2400 CL16 SODIMM

Work fine. I am HAPPY.

But, one problem.
In CPU-z utility modules detected right.

In BIOS - unknown modules. And RAM freq = 2133 (min freq, safe mode) 

I don't care, but it's sad.

Thanks.

[Huffer]

BIOS is only written to detect stock HP modules and the Manual makes it clear that DDR4-2400 should be installed but will "bridge" (downclock) to 2133. So its working as intended. Thanks for letting us know it worked for you. We think we know what we are talking about but its good to get the occasional confirmation,