Installed 32GB and Hardware reserved 18.1 GB

[ra_2025]

My laptop model = HP Pavilion Gaming 15-ec0101ax

BIOS version / Date = AMI F.20,  2024-05-06

Baseboard Product = 86D5
Baseboard Version = 96.45

Current OS = Win 11
Preinstalled OS = Win 10
Preinstalled Ram = 8GB

I installed 32GB (16 GB x2) ram replacing my 8GB ram which came default with my hp laptop.
Laptop boots normally.

I dont game, have not tweaked any bios setting or video card setting.
Why 18.1GB gets Hardware reserved ?
Previously on 8GB, 2.1 GB got reserved for AMD graphics card and that's understandable.

problems
1- Hardware reserved should be 2.1 GB and not 18.1 GB. How to fix this?
2- How can I create a bootable BIOS USB and also how to select the correct version to download? (I get 4 different options on "Software and Drivers for HP Pavilion Gaming - 15-ec0101ax" page. I want to have a BIOS backup , just in case.

Please help me out at the earliest.
I need my laptop for work, I am facing this problem since 5 days and finally gave up finding the solutions.

[Screenshot attached]

Hardware reserved problem

[ra_2025]

Posting my Ram specs, taken from cpuz

slot 1 - Crucial - CB16GS2666.C8FT
slot 2 - Crucial - CT16G4SFS8266.C8FE
Both are are =  Single rank - CL19 - 1.2V rams

Hope this helps.

[Hawks_Eye]

Hi @ra_2025 

Welcome to the HP Support Community! We're here to help you get back up and running.

The unusually high 18.1 GB hardware reserved memory is likely due to a RAM compatibility or BIOS mapping issue. To correct this, reseat the RAM, test modules individually, and update BIOS using a bootable USB created from HP’s official firmware.

You’ve done a thorough job documenting your setup and steps, and I understand how disruptive this issue has been. 

Let’s address both concerns methodically:

 

1. Fixing the 18.1 GB Hardware Reserved Memory

This value should not exceed 2–4 GB under normal conditions. Since your system boots and recognizes 32 GB, the issue is likely tied to memory mapping or module compatibility.

Steps to resolve:

Reseat both RAM modules
Power off the laptop, remove the battery if accessible, and reseat both Crucial modules firmly. Ensure they’re fully seated and matched in voltage and speed.

Test modules individually
Insert one module at a time and boot into Windows.
Check Task Manager > Performance > Memory to see if hardware reserved drops.
If one module causes the spike, it may be incompatible or faulty.

Run UEFI Memory Test
Restart the laptop and press F2 at startup to enter HP Hardware Diagnostics.
Run the Memory Test under System Tests.
This checks for low-level faults that Windows may not detect.

Update BIOS to latest version
Even though you’re on F.20, reapplying the update can reset memory mapping.
Follow the USB creation steps below.

 

2. Creating a Bootable BIOS USB for HP Pavilion Gaming 15-ec0101ax

Steps to create and use the BIOS recovery USB:

Visit the official HP support page:
HP Pavilion Gaming 15-ec0101ax Drivers & Software

Under BIOS, download the latest version listed for your OS (Windows 11).
Look for the file labeled F.20 Rev.A or newer.

Run the downloaded file.
When prompted, select Create Recovery USB Flash Drive.
Insert a blank USB drive (at least 1 GB).
Follow on-screen instructions to complete creation.

To apply the BIOS update:

• Insert the USB into your laptop.
• Restart and press Esc, then F10 to enter BIOS.
• Select Update BIOS or HP BIOS Update from the menu.
• Follow prompts to apply the update.

This process also creates a backup of your current BIOS, stored on the USB.

Your Crucial modules are single-rank, CL19, 1.2V — technically compatible with your board.
However, mixing part numbers (CB16GS2666.C8FT and CT16G4SFS8266.C8FE) may cause mapping inconsistencies.
If reseating and BIOS update don’t help, consider testing with matched pairs.

Avoid registry edits or third-party memory tweaks.
Stick to BIOS and hardware-level adjustments only.

Let me know if you’d like help interpreting the results of the UEFI memory test or navigating the BIOS update menu — I can guide you screen by screen.

If my response helped, please mark it as an Accepted Solution! ✅ It helps others and spreads support. 💙 Also, tapping "Yes" on "Was this reply helpful?" makes a big difference! Thanks! 😊

Take care, and have an amazing day!

Regards, 

Hawks_Eye

[ra_2025]

1- "... reserved memory is likely due to a RAM compatibility ... "
I did some research and asked few people about correct RAM to buy. I noted my original 8GB RAM specs, which are -  Kingston-SK Hynix 8GB DDR4 ram - 2666 Mhz - CL17 - 1.2V.
The RAMs which I ordered have exact same spec except being CL19 and both RAMs have same Jedec table and readings of each other (from cpuz). If you want I can post the screenshots.

2- "To correct this, reseat the RAM, test modules individually, "
I have seated it multiple times, have also swapped out each other, doesn't fix the problem.
Here is what I already did -
i) Ram 1 in slot 1, empty slot 2 = System boots, hardware reserved = 2.1 GB
ii) Ram 2 in slot 1,  empty slot 2 =  System boots, hardware reserved = 2.1 GB
iii) Ram 1 in slot 2, empty slot 1 = Fail to boot. Black screen, Fans work, cpu light doesnt blink.
iv) Ram 1 in slot 2, empty slot 1 = Fail to boot. Black screen, Fans work, cpu light doesnt blink.
v) Ram 1 in slot 1 + Ram 2 in slot 2 = System boots, hardware reserved = 18.1 GB, task manager shows 32GB.

vi) Ram 2 in slot 1 + Ram 1 in slot 2 = System boots, hardware reserved = 18.1 GB, task manager shows 32GB.
note- Whenever system booted, task manager didnt show any spike in memory graphs / graphics graph. Fans works normally too.

3- "..Restart the laptop and press F2 at startup to enter HP Hardware Diagnostics....."
I downloaded HP support assistant and  HP Hardware Diagnostics .exe files and All tests were passed.

4- "...Visit the official HP support page.."
I am already logged in.
Clicking the link leads to this page "https://support.hp.com/in-en/error/404?source=SWD"


Questions
1- Do I have to do Memory Test again at reboot time ?
2- Please give me the link again to download BIOS file.

Thank you for reply.

[Hawks_Eye]

Thanks for replying @ra_2025 

I appreciate your time and efforts!

The 18.1 GB hardware reserved memory is caused by a mismatch in how your Pavilion Gaming 15-ec0101ax maps the two Crucial RAM modules together. Each module works fine alone (2.1 GB reserved), but when paired, the system reserves far more due to compatibility or slot mapping. You should run the memory test again at reboot (F2 UEFI diagnostics) because it checks at firmware level, not just within Windows. 

For the BIOS, the correct download page is here: HP Pavilion Gaming 15-ec0101ax Drivers & Software.

 

Why the Reserved Memory Spikes

• Single module works fine: Each RAM stick individually reserves ~2.1 GB, which is normal for integrated graphics.
• Dual configuration issue: When both are installed, the system reserves 18.1 GB. This points to a mapping conflict between the modules or the slot controller.
• Slot behavior: Your test shows one slot fails to boot with either module alone. That suggests the second slot may not fully support the CL19 Crucial modules, even though specs match.

 

Steps to Fix

Run UEFI Memory Test at Boot

• Restart, press F2, and run the memory test outside Windows.
• This checks low-level compatibility and can reveal slot/controller issues that Windows diagnostics miss.

BIOS Update via Recovery USB

• Download the latest BIOS from the HP support page above.
• Run the installer in Windows and choose “Create Recovery USB Flash Drive.”
• Boot from the USB, press Esc → F10, and select “Update BIOS.”
• This refreshes memory mapping and stores a backup of your current BIOS on the USB.

Matched RAM Modules

• Even though both Crucial sticks are technically compatible, mixing part numbers (CB16GS2666.C8FT vs CT16G4SFS8266.C8FE) can cause mapping inconsistencies.
• If BIOS update doesn’t fix it, test with a matched pair (same part number, CL, rank).

Avoid Registry Tweaks

• Do not attempt registry edits or third-party memory tools. Stick to BIOS and hardware-level adjustments.

Risks and Trade-offs

• Slot limitation: If one slot consistently fails with single modules, the board may only fully support certain RAM profiles.
• Performance impact: With 18.1 GB reserved, you effectively only have ~14 GB usable, which defeats the purpose of upgrading.
• Solution path: BIOS update and matched RAM are the most reliable fixes. If the slot itself is faulty, service may be required.

Next Step for You:
Run the UEFI memory test at boot (F2) and then update BIOS using the HP support link above. If the reserved memory persists, consider replacing with a matched pair of CL17 or CL19 modules that share identical part numbers. 

Regards,

Hawks_Eye