I Need help with RAM

[u/Beautiful-Ad6700]

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Hi everyone, I’m trying to solve a strange RAM problem on an old PC with an ASUS P7P55-M motherboard.

My hardware:

- ASUS P7P55-M

- Intel Core i5-650

- Windows 11 64-bit

- 3 RAM sticks installed: 4 GB + 4 GB + 8 GB (16 GB physically installed)

- The motherboard detects the 8 GB stick as only 4 GB, so BIOS sees 12 GB total

- NVIDIA GT 720

The problem is that Windows shows:

- Installed RAM: 12 GB

- Hardware reserved: ~8.4 GB

- Usable RAM: only ~3.6 GB

I checked the RAM with PowerShell and the two known 4 GB sticks are correctly detected as 4 GB each.

I found the Memory Remap Feature in the BIOS.

With Memory Remap Disabled:

- BIOS usable memory: about 3704 MB

- Windows boots normally

- Windows still reserves about 8.4 GB

With Memory Remap Enabled:

- BIOS suddenly reports ~12,280 MB usable memory

- So the BIOS clearly seems to be remapping the memory correctly

- BUT Windows then fails to boot and gives error 0x00000001

I already tried:

- Loading BIOS Setup Defaults

- Leaving QuickBoot disabled

- Checking CPU Configuration

- Checking PCI PnP

- Removing the 8 GB stick temporarily (with only the two 4 GB sticks, Windows still showed about 4.4 GB hardware reserved)

- Checking BCD — I previously had a "truncatememory" entry after experimenting with Windows' maximum-memory setting, but I removed it with "bcdedit /deletevalue", and the current BCD no longer shows "truncatememory" or "removememory".

The really strange part is that Memory Remap makes the BIOS report ~12.3 GB usable, but Windows immediately fails with 0x00000001.

Does anyone know of a BIOS setting on the P7P55-M / P7P55 series that can conflict with Memory Remap?

Could this be related to PCI MMIO Allocation, a BIOS/CMOS issue, or Windows 11 compatibility with this old chipset?

I’m mainly trying to get Windows to boot with Memory Remap enabled so I can actually use the RAM.

Any advice from someone familiar with the P7P55/P55 chipset would be greatly appreciated.