I would not recommend flashing it unless you know what you're doing. If Dell has the VGA BIOS have you tried uninstalling it maybe? That might fix the issue but if it doesn't then Use Techpowerups NVFlash tool with the correct vBIOS.

Here is the Dell VBIOS suggestion for my laptop. I've never installed a VBIOS (done most everything else). How would I uninstall the old bios? Is there a how-to tutorial?

you don't uninstall a BIOS, that is not a good suggestion.  VBIOS is just like System BIOS.  the video card will not function without a BIOS installed.  

if you install an incompatible BIOS or VBIOS onto hardware, it will brick it.  There is also a chance you can reduce performance.  the VBIOS controls the clock profiles, if you install a BIOS for a lesser TDP version of your GPU, it will act like that lower TDP chip...  lowering performance.

All that that aside, I was looking to see if the R4 supported resize bar function.  I saw that you have to be up to date on the video driver but I am...  no luck so far on setting it.

My system does say it is supported (nvidia control panel, system information)

Resizable BAR = YES

driver version = 465.89

VBIOS = 94.06.15.00 C

note my VBIOS is newer than the one in your link.  I got my M15 R4 a few days ago.  love the system!  (RTX 3060 115W version)

you might need to force the display mode to NVIDIA GPU to be able to set it.  Maybe the Optimus setting will also allow setting it.  

(nvidia control panel, manage display mode)

I also found this, which says you must have the driver I've got or higher, game ready version.

https://www.nvidia.com/en-us/geforce/news/geforce-rtx-30-series-resizable-bar-support/

Thank you for your input. But Im not following your tip to "force the display mode to NVICIDA GPU." It sounds simple, but its not there that I can find. Attached is a screenshot of is what I see within the nvidia control panel (I dont see "manage display mode"). 

On my system, the option is in the top section (I have 4 items in the first section and you have 3 in your screenshot). 

however, because you have the lower sections with all the graphics details, you already have it forced to dedicated GPU only.  the nvidia control panel will only show those other sections when the nvidia gpu is enabled in dedicated mode.

did you see the resizable bar = yes in the system information at the bottom of the control panel window?

My resizable bar setting in NVIDIA control panel says "no" (as below), but that might change to "yes" if I could update the VBIOS Dell offers on their website....

NVIDIA System Information report (partial)
[Display]
Operating System: Windows 10 Home, 64-bit
DirectX version: 12.0
GPU processor: NVIDIA GeForce RTX 3080 Laptop GPU
Driver version: 465.89
Driver Type: DCH
Direct3D feature level: 12_1
CUDA Cores: 6144
Resizable BAR No
Dynamic Boost 2.0 Yes
WhisperMode 2.0 No
Advanced Optimus No
Maximum Graphics Power 140 W
Core clock: 1605 MHz
Memory data rate: 14.00 Gbps
Memory interface: 256-bit
Memory bandwidth: 448.06 GB/s
Total available graphics memory: 24457 MB
Dedicated video memory: 8192 MB GDDR6
System video memory: 0 MB
Shared system memory: 16265 MB
Video BIOS version: 94.04.40.00.10
IRQ: Not used
Bus: PCI Express x8 Gen3
Device Id: 10DE 24DC 0A741028
Part Number: 4735 0010

that helps identify the possible issue.  your VBIOS is older than the update and the update is older than my system.

you have two paths. 

1) try the VBIOS update, it looks like it applies to your system.  Updating a VBIOS is just like updating system BIOS or a firmware for an SSD.  you run the installer and reboot when needed.   never unplug AC during the update and don't use the system while updating.  There is no mention that this VBIOS enables the function.

2) contact support to see if you can get the same VBIOS version I have and update to that one.  We know my version works.

I'm a little confused about why your report doesn't support Advanced Optimus.  I thought all m15 R4 supported that mode.  

Yes, its odd. The only thing I can figure is that your GPU (RTX 3060 115W version) is a slightly diff version than mine RTX 3080).

The "Advanced Optimus" may be the differentiating factor here. 

I recently ordered the M15 R4 and while building the configurations noticed not all the choices for M15 R4 offered  Advanced Optimus. Sometimes the Dark Side of the Moon displays will list it while the Lunar Light option will not for the same build select page.

Rather tricky and easy to miss and pricing seems sliced and diced to few dollars sometimes. I hope they will just offer the Advanced Optimus as a clear, separate option box so people don't miss it. 

I am not sure if that is the issue here for the resizable bar, but could be.

Any luck with the VBIOS update?

I have an additional data point, a non-alienware laptop.  The VBIOS on this system is a bit older than the one you have but bar is supported.  Because the VBIOS comes from NVIDIA and not DELL, it is possible to compare at some level the versions.  This probably means that it can be turned on or off by the vendor.

GTX 3070 140W

VBIOS 94.04.3F.00.50

advanced optimus = NO  (But I know it has regular optimus)

resizable bar = yes

driver 466.11

I experienced the issues of the last poster, I originally bought a m15 R3 2080 super 300Hz and discovered that the design of that laptop didn't allow using the iGFX for battery saving but if you had the 144Hz version it would have.  Dell doesn't do a great job of specifying the display features and capability.  that was s driving factor in my choice of R4 with Advanced Optimus and 144Hz screen.  

I have he M15 r4 with the RTX 3070 (similar to your configuration). I flashed the latest Dell System BIOS, the VBIOS, and downloaded the latest nvidia driver with resize bar support. Even though the nvidia control panel reports rebar as supported, it is not enabled. How you can tell is if you download TechPowerUp GPU-Z, it reports rebar as disabled.

This means that Dell needs to update the System BIOS to either give us the option to switch it on/off, or have it on by default. I know this because I performed the same procedure on my Desktop RTX 3090/Z390 motherboard and it reports rebar as on after the BIOS is set.

Thanks for the thorough response. I am curious, which file did you use to update your vBios? I tried this one, but the install was "forbidden": 

NVIDIA GeForce RTX 3060/3070/3080 Firmware Update Utility BIOS 24 Feb 2021
Version X00, X00
File Name VBIOS_Flash.exe
File size 61.1 MB
Description This package contains the NVIDIA GeForce RTX 3060, 3070, and 3080 GPU VBIOS version 94.04.42.00.14.

I used the same file that you have shown there, but didn't get a forbidden error. Try closing all applications, and then right click on the file and run as Administrator (hopefully that works for your). If successful, the VBIOS version will match what I have shown in the GPU-Z above.