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Requirements for Resize BAR?

Nov 26, 2005
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I upgraded to a RTX 30 series GPU and I think I may have initially installed my OS with CSM Compatibility enabled, however my drive is formatted in GPT. I think this may be the reason why I cannot enable 'Above 4G Decoding, and Resize BAR. Is anyone familiar with the in's and out's of Resize BAR? I'm hoping I don't have to do a reinstall.

Helps,

Thank you!
 

maluckey1

Senior member
Mar 15, 2018
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Resize bar will not work in CSM mode. In UEFI, disable CSM, and once you boot into your OS, you can enable Resize Bar by whatever method that your vendor provides.

In my case, with an EVGA 3070, I had to install Precision X1, which automatically updated the card and enabled Resize Bar. CAUTION!! Booting into CSM is not an option for many combinations once this is done. I cannot boot into CSM without using onboard graphics.
 
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Nov 26, 2005
14,773
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106
Resize bar will not work in CSM mode. In UEFI, disable CSM, and once you boot into your OS, you can enable Resize Bar by whatever method that your vendor provides.

In my case, with an EVGA 3070, I had to install Precision X1, which automatically updated the card and enabled Resize Bar. CAUTION!! Booting into CSM is not an option for many combinations once this is done. I cannot boot into CSM without using onboard graphics.
What combination is required to boot into the bios? That's where I'm at.
 

Shmee

Memory and Storage, Graphics Cards
Super Moderator
Sep 13, 2008
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What motherboard are you using, and what firmware revision? You may need to update your motherboard's UEFI for the feature to be available. Likewise, you may need to upgrade your video cards firmware as well.

I doubt you have to reinstall windows. I don't think CSM disabled is a requirement, at least, I am pretty sure it is off for my motherboard, though I do boot in UEFI mode from my Sabrent. Resizeable bar is indicated as enabled in the Nvidia control panel. Though, this may all depend on your specific hardware. Can you list your specs?

Also, here is the Nvidia page with requirements. https://www.nvidia.com/en-us/geforce/news/geforce-rtx-30-series-resizable-bar-support/
 
Nov 26, 2005
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Xtreme F33, updated the GPU firmware. I've successfully enabled Resize BAR but I cannot get back into the bios to change any settings. Once I enabled Above 4G decoding, Enabled Resize BAR support, CSM automatically got disabled. Rebooted and I no longer can get into the bios. Fast boot is disabled, Gigabyte boot logo is disabled, I've tried doing the Windows 10 recovery option that gives you the option to boot into the UEFI and booting just blows past it and loads windows. I'm using a 5800X in both my X570 rigs.
 

Shmee

Memory and Storage, Graphics Cards
Super Moderator
Sep 13, 2008
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Ok, so from what I am reading, CSM support needs to be disabled. I guess I must have missed that, and it happened automatically. Some users say you could try clearing CMOS, and then go back in. Others say it may be a displayport issue, and to try HDMI or something, or to turn off the monitor first.

Just to confirm, you are spamming the delete key and not able to get into UEFI setup? You could try the workarounds, (clearing CMOS, fiddling with monitor or cables) and then once able to get back in, you might want to enable a delay for a couple seconds before booting, assuming your board has that option.
 
Nov 26, 2005
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Yeah, I've tried spamming the delete key when booting.. I'm at a loss

Side question: was thinking about dropping my HD6450 passive cooled card for like the best passive cooled GPU card for my daily rig. I still keep getting display drop-outs. Monitor shuts off for a brief second then comes back on. Event viewer says "Display driver amdkmdap stopped responding and has successfully recovered." That's been going on for since i set the machine up. Any suggestions?
 

Shmee

Memory and Storage, Graphics Cards
Super Moderator
Sep 13, 2008
5,262
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Sounds like that card may have an issue. It is pretty old after all. Have you tried a different driver version?
 
Nov 26, 2005
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Just the latest one I could find. I like silent PCs when not gaming. I could try my 1070 FE in it however the PSU is very old
 
Nov 26, 2005
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I can confirm Resize BAR enabled + Display port 1.4 on my PG259QNR does not communicate with the GPU during boot for bios access. I just swapped out my PG259QNR with my Omen X25f and I was able to see AMERICAN MEGATRENDS boot screen and enter the DELETE key for bios access. PG259QNR 360Hz Display port 1.4, Omen X25f 240Hz Display port 1.2

EDIT: It could be something with the Display port revision, Asus monitors, or 360Hz. I haven't done any further testing. This was my initial finding and observation.
 
Last edited:

maluckey1

Senior member
Mar 15, 2018
206
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71
Display port bug here too, but with different hardware. My setup will automatically switch to CSM support if the monitor was turned off at bootup. Also, if I grab the HDMI cable and plug it into my laptop to use the big screen, sometimes when I reboot, the computer will switch to CSM.
EDIT: It could be something with the Display port revision, Asus monitors, or 360Hz. I haven't done any further testing. This was my initial finding and observation.
In my case this behavior ONLY happens when dealing with display port, and never with my old crappy office monitor. I think that you may be on to something, that it might have something to do with some gaming monitors and display port.
 
Nov 26, 2005
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So another question arises as I use an HDMI cable and I can now see the AMERICAN MEGATRENDS screen as I boot, for bios access, however the variable is that HDMI is capped at 240Hz. I have yet to try the Display Port cable (1.4) at 240Hz. There seems to be a disconnect with the hardware communication during boot somewhere. Not sure now if it's the Display Port revision or the monitor frequency.
 

maluckey1

Senior member
Mar 15, 2018
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HDMI 2.1 I assume?

Yeah, I feel your pain. I just encountered that if I start the computer with the monitor turned off, then turn the monitor on, UEFI switches to CSM and I get a black screen and no way to boot without using CPU graphics. It never did this before re-flashing the video card to enable Resize BAR.

It's a pain because I have to unplug one of the power connectors to the video card so the mobo doesn't see it unplug the display port cable, plug in the CPU graphics HDMI to do so.

I'm leaning towards GPU firmware and resize bar quirks as the cause for these system quirks. About the only thing our systems have in common is a 30 series card. I don't believe in coincidences all that much

M
 
Nov 26, 2005
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HDMI 2.0 on the PG259QNR.

Just tried the Display Port (1.4 for new readers: PG259QNR) @ 240Hz and I did not see the AMERICAN MEGATRENDS bios screen. No bios access.

So:
-Display Port 1.2 240Hz on my Omen X25f will allow access into the bios with Resize Bar enabled.
-HDMI 2.0 240Hz on my PG259QNR will allow access to the bios ...
-Display Port 1.4 on my PG259QNR will not allow bios access @ either 240 or 360Hz with Resize BAR enabled.

I've tried the windows recovery option. Changing Fast Boot options.

EDIT: my GPU has 1 x HDMI 2.1, 3 x Display Port 1.4a
 
Last edited:

maluckey1

Senior member
Mar 15, 2018
206
83
71
That's interesting. I don't have fast boot enabled, but still have black screen issues.

Have you tried:

- booting into UEFI on HDMI-only connection
- ensure CSM is still disabled
- save/exit + hard shutdown
- connect only display port
- boot

On my other setup without CPU graphics, I had to actually swap an older GTX 770 into the system THEN do the above steps, and while it was shutdown, swap back the 30 series card. Worked like a charm
 
Nov 26, 2005
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When Resize BAR is enabled CSM automatically gets disabled in my bios on my X570 Xtreme.

Seeing replies from users saying that Display port 1.4 (with other monitors) + 3090 + X570 with Resize BAR enabled and they are able to reach the bios. Hmmm
 
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Golgatha

Lifer
Jul 18, 2003
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The nVidia website has some pretty good resources. For the one system I bothered to jump through the hoops on, I updated the video firmware on my 3090, installed the latest nVidia drivers, updated the motherboard UEFI, went into the UEFI and enabled the resizable bar feature via a new drop down menu, and checked all the pieces were in place via eVGA's Precision X1 software. I already had CSM disabled, so I skipped this step. Nice boosts to Horizon 4 and Cyberpunk 2077.

 
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