PC won't boot using two RAM cards

[DaedalusDaVinci]

I attempted to install a second RAM card in my PC but get the memory error and it won't boot. I've put my original RAM card in both slots and confirmed both work, as well as the new RAM card to confirm it works. The problem only occurs when both are in at the same time. They are the exact same brand and everything so as far as I can tell it's not a compatibility issue

[Prométhée]

Hi

sorry, most often if two modules do not work together, it is because they are incompatible with each other
It could have a cause, which I don't know, but I assure you that in 99% of cases, this is the problem
Try to order the same module

if this one

HP Pavilion 690-0010 Gaming Desktop PC Product Specifications

8 GB

• Amount: 8 GB
• Speed: PC4-21300 MB/s
• Type: DDR4-2666

Sunflower motherboard specifications.

• Dual channel (2 DIMMs per channel) memory architecture
• Two DDR4 UDIMM (288-pin) sockets
• Supports PC4-19200 (DRR4-2400)
• Supports 4 GB and 8 GB DDR4 UDIMMs
• Supports up to 4 GB on 32-bit systems

  note:

  32-bit systems cannot address a full 4.0 GB of memory.

• Supports up to 32 GB (unbuffered) on 64-bit computers

watch out for incorrectly inserted modules, this can also happen

[DaedalusDaVinci]

They are the exact same module, I made sure to order the same one

[Prométhée]

it is the same exactly the same reference hp?

https://support.hp.com/us-en/drivers/selfservice/hp-pavilion-gaming-desktop-pc-690-0000a/37730935

I recommend updating the bios, check if there is not a problem of this type mentioned
but before, I would advise you more to replace the old module
Before try this
turn off the computer, unplug everything except keyboard / mouse / screen
Remove the CMOS battery
Long press the power button
Remove both memory modules
, replace the two modules correctly
reconnect restart
If not better, it's up to you, replace the old module / bios update

[DaedalusDaVinci]

I have tried replacing the old module, and updating the bios, but no luck. I haven't tried removing the CMOS battery yet though 

[Prométhée]

Sorry, I don't understand, you obviously don't give me all the information?
you said you tried an old one and a new one at first, that's all..
you didn't tell me you tried two new modules?

An old module works in slot one and two!
a new one also works in slot one and two
Both sets do not work!

If you have already tried everything, then there are not too many options.
make a summary of everything you have tried, with reference photos of the modules etc, also check each module with this,

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