*credit to @teknicalissue for the screenshot, even though this is not ReBar, but it shows the board can use large bar size with Tesla P40 under Above 4G Decoding without issue.
ME Firmware Ver: 9.1.37.1002 → 9.1.40.1000
Disk Controller
EFI Intel RST for SATA - 14.8.0.2377 → 14.8.2.2397
OROM Intel RST for SATA - 13.1.0.2126 → 14.8.2.2397
OROM Intel RST for SATA - 14.8.0.2377 → 14.8.2.2397
Network
EFI Intel Gigabit Driver - 0.0.09 → 0.1.02
OROM Intel Boot Agent CL - 0.1.06 → 0.1.16
Inserted Modules:
ReBarDxe v0.3
NvStrapsRebar v0.4-rc1
Misc:
All Microcodes updated to the latest
MMCFG Base Increased from 1GiB to 2GiB
MMIO High Size increased from 256GiB to 1TiB
How To Enable Resizable Bar
Normal Resizable Bar: Use ReBarSate from here, And Run as Admin.
Nvidia Turing (GTX 1600/RTX 2000): Use this, And Run as Admin.
You need to enable Above 4G Decoding for Resizable Bar and Disable CSM/Legacy (boot to UEFI only). To enable it, go to bios → Boot → Above 4G Decoding and enable it.
I’m running a homelab on an old Asus X99-A PC using TrueNAS Scale. My primary challenge is maximizing performance for media transcoding and LLMs but unfortunatley my switch to Truenas scale means the NVIDIA Quadro 1000 is limited due to kernel compatibility issues with modern drivers.
Whilst I will likely assign the quadro to a VM for LLMS my GPU focus has switched to the Intel Arc A310 card… however, its performance is restricted by a BIOS limitation (256MB VRAM).
With performance left on the table, my goal is to get rebar support on this motherboard if possible. I’ve tried a few different things and seem to be hitting a brickwall, almost certainly because of PEBKAC issues.
HARDWARE SPECS
Asus x99-A motherboard - running Beta BIOS 4101 (2019/07/17)
Intel i7-5820K
Micro 4x16 GB sticks
REQUEST
I’m hoping to get a modded bios file that already has rebar support added, the current bios has 4G decoding so I suspect we’re 1/2 way there. I’m hoping to use USB flashback for this becasue the whole FPT thing looks scary as funcky tomatoes though with the right guidance I’m willing to give it a go.
The rabbit hole of versions etc… led me to the point of joining an admittidly great forum to ask for help and whilst I’m fairly tech savvy I’m also very new to this particualr game!!
Lastly, I’m happy to donate a coffee for efforts made - I’m very appreciative of any assistance, cheers!!
BIOS Information
Vendor: American Megatrends Inc.
Version: 4101
Release Date: 07/10/2019
Address: 0xF0000
Runtime Size: 64 kB
ROM Size: 16 MB
Characteristics:
PCI is supported
APM is supported
BIOS is upgradeable
BIOS shadowing is allowed
Boot from CD is supported
Selectable boot is supported
BIOS ROM is socketed
EDD is supported
5.25"/1.2 MB floppy services are supported (int 13h)
3.5"/720 kB floppy services are supported (int 13h)
3.5"/2.88 MB floppy services are supported (int 13h)
Print screen service is supported (int 5h)
8042 keyboard services are supported (int 9h)
Serial services are supported (int 14h)
Printer services are supported (int 17h)
ACPI is supported
USB legacy is supported
BIOS boot specification is supported
Targeted content distribution is supported
UEFI is supported
BIOS Revision: 5.11
Handle 0x0002, DMI type 2, 15 bytes
Base Board Information
Manufacturer: ASUSTeK COMPUTER INC.
Product Name: X99-A
Version: Rev 1.xx
Serial Number: Redacted
Asset Tag: Default string
Features:
Board is a hosting board
Board is replaceable
Location In Chassis: Default string
Chassis Handle: 0x0003
Type: Motherboard
Contained Object Handles: 0
Handle 0x0028, DMI type 10, 6 bytes
On Board Device Information
Type: Video
Status: Enabled
Description: To Be Filled By O.E.M.
Handle 0x005A, DMI type 41, 11 bytes
Onboard Device
Reference Designation: Onboard IGD
Type: Video
Status: Enabled
Type Instance: 1
Bus Address: 0000:00:02.0
Handle 0x005B, DMI type 41, 11 bytes
Onboard Device
Reference Designation: Onboard LAN
Type: Ethernet
Status: Enabled
Type Instance: 1
Bus Address: 0000:00:19.0
Handle 0x005C, DMI type 41, 11 bytes
Onboard Device
Reference Designation: Onboard 1394
Type: Other
Status: Enabled
Type Instance: 1
Bus Address: 0000:03:1c.2
Handle 0x0071, DMI type 13, 22 bytes
BIOS Language Information
Language Description Format: Long
Installable Languages: 3
en|US|iso8859-1
fr|FR|iso8859-1
zh|CN|unicode
Currently Installed Language: en|US|iso8859-1
@versey@Koekieezz
If you agree, I would like to merge this new “Request” thread with >this< already existing thread, where such modded BIOS has been already offered.
Please give me your feedback.
I downgraded to latest non BETA BIOS from asus being 3801 using EZ Flash (BIOS GUI)… loaded optimised defaults then flashed the X99A_Complete.rar BIOS using USB flashback worked i.e.
16 GB stick, Fat32, X99A.CAP on root, no other files, insert to the CORRECT USB port (should be obvious), shut down system, hold Flashback button for 2-3 seconds which blinked slowly while interrogating the file, then flashed quicker when writting, then LED went out when completed.
After a long power on cycle (subsequent ones at normal speed) I loaded optimised defaults, disabled CMS, configured the UEFI boot drive, set secure boot to other OS, cold rebooted, enabled 4G decode but Truenas still reported 256 limitation as per
@versey Have you confirmed if bios flashback succesfully flashed the modded bios? Might need to double check bios version you were was and currently now if you’re not sure.
Since you already in the correct step on setting up the bios (CSM Disabled, Above 4G Decoding Enabled) assuming that you’ve flashed the modded bios succesfully, to activate rebar, If pci=realloc or pci=realloc=on didn’t work, you might need to use ReBarState (run as admin) in the host pc, set/enter value 32, enter, and reboot. Rebar should work shortly after reboot.
IDK if the executable works in linux, but definitely it worked in windows.
Yeah I can confirm it went from 3801 to 4101 so the bios updated fine. I ran both those commands on a sudo sh terminal and didn’t get any results, since this is a homelab I have to wait till noones using it’s services but will load up Windows onto an SSD, run ReBarState as explained then see what happens, fingers crossed
If you managed to boot on windows, you can verify if above 4g decoding is functioning normally and rebar is activated after using the executable (and reboot afterwards), by going to Device Manager → View → Resource by type → Large memory → see if your gpu is there. If your gpu is listed under large memory (except the Quadro P1000 because it does not support rebar obviously), you might able to proceed to go to bios and save the profile. Idk if asus save the profile including the configured nvram values, but if it does, you might not need to go to windows again, just in case you replace cmos and everything has been reverted to default, you could try to load up the profile and see if rebar is activated again.
