Hi everyone, I’ve read a ton of threads on this argument but I haven’t been able to figure the procedure out myself.
I’m really interested in testing the perfomance difference this mod can provide to this old HW paired with modern GPUs.
So I hope someone can do the magic for me and, if possibile, enable above 4G decoding in the two attached BIOS.
It seems on this moderboard above 4G decoding is enabled by default. If that’s true, what am I missing in order to enable Smart Access Memory or Resizable BAR?
@Kuri0 regarding the GRUB testing sadly these two PC are not running linux. I have two linux servers but they are not in the scope.
If this step is necessary I should setup a new dual boot.
Also 4G decoding doesn’t give you smart access memory/resizable BAR on Windows (only on Linux).
Though I recently developed a module to get it on older motherboards you could try that if you want. Send screenshot of Device Manager with “View->Resources by Type” with “Large Memory” expanded if you want me to see if it’s possible on your motherboard.
Download the modGRUBShell.efi. Place it in EFI/Boot folder on a USB drive and rename it to bootx64.efi. Make sure you have the USB drive marked as bootable and you should be able to boot it. From there you can use setup_var command to enable it.
For example on the Z97 it would be setup_var 0x1 0x1 because we can see VarOffset (the first value in both command and ifr output) is equal to 0x1 in the following. If anything goes wrong you can just pull the CMOS battery back to default
P67 should work with the module no problems. However the GPU you have in it (R9 280X) seem doesn’t support resizable BAR (according to GPU-Z) and you also need to make sure you’re using a 3rd gen CPU and PCIe 3.0 is working.
Sorry, the p67 rig has Arch installed and amdgpu should support resizable bar. Right now it’s still 256mb on both Linux and windows.
Could you mod the BIOS I’ve provided?
No, nothing pops up on the z97 board. Could it be beacuse of the PLX chip? It has a lot of PCIE.
if the hardware does support it linux should automatically enable resizable BAR (given that 4g decoding is enabled). 3770k is capable of resizable BAR but R9 280X isn’t from what I know.
Try contacting ASRock about broken 4G decoding there’s a possibility that they still support the Z97 motherboard. Another thing you could try is setting the setup_var value to 0 (setup_var 0x1 0x0), rebooting and then re enabling it. I had an issue of it being 0x1 but not enabled and doing that fixed it for me.
I mod your z97 provided bios and in advanced menu i unlocked the setting pci subsystem that have the setting above 4g decoding. You can enable or disable. Default setting is disabled. Z97Ex9_2.rar (4.4 MB)