Boot Device Not Found after installing new RAM

[Mark967]

I have HP Pavilion gaming 15-ec0007r. I have tried to update my RAM from 8 gb ( two 4gb sticks) to 16 gb (two 8 gb sticks, crucial 3200mhz). After installing new RAM my laptop says: CMOS Checksum is invalid, then reboots to a screen of "Boot device not found". Pressing ESC, F2 or F10 doesn't work. 

Installing one stick of RAM or old one results in the same Boot Device Not Found screen.

[Deep_World]

Hi @Mark967,
 
Welcome to the HP Support Community!

Thanks for reaching out!

Sorry for the inconvenience caused don’t worry let me help you.

To better understand the issue, could you please provide a few more details?

• Did you make any BIOS/UEFI changes before or after installing the new RAM?
• When you reinstalled the original RAM, did you reseat both sticks firmly and check that the slots are clean?
• Have you noticed if the hard drive/SSD is being detected in BIOS at all, or does it fail to show up entirely?
• Was the laptop working normally right before the RAM upgrade, with no boot issues?

Troubleshooting steps to try

1. Power reset
   • Disconnect the power adapter 
   • Hold down the power button for 15–20 seconds to discharge residual power.
   • Reconnect only the original RAM and try powering on again.
2. Reseat RAM and storage drive
   • Remove and reinstall the RAM sticks carefully.
   • If possible, check that your storage drive (HDD/SSD) is firmly connected sometimes reseating RAM can slightly shift other components.
3. Clear CMOS / Reset BIOS
   • Since you saw a “CMOS checksum invalid” message, the BIOS may have been corrupted or reset.
   • If your model has a CMOS battery, removing it briefly and reinserting can help. Otherwise, try pressing F10 repeatedly right after powering on to enter BIOS setup.
   • If you can access BIOS, restore default settings and save.
4. Check boot order
   • If you manage to enter BIOS, confirm that your storage drive is listed and set as the primary boot device.
   • If the drive isn’t detected, that points to a connection or hardware issue with the drive itself.
5. Test with one RAM stick at a time

• Try booting with just one stick of RAM (both new and old) in each slot to rule out slot or stick issues.

I hope this helps.

I'm glad I could help! 😊 If this resolved your issue, please mark it as "Accepted Solution" and click "Yes" on "Was this reply helpful?" Your feedback not only keeps us going but also helps others find the solution faster! 

Take care and have an amazing day ahead! 

Best regards,

Deep_World