Can anyone confirm resizable BAR support for AMD CPUs?

[SamSegal]

Introduction:

Spoiler

Hi all,

I've recently bought the Intel Arc A750 (ASRock challenger OC version) as an upgrade to my GTX 1060.
Painfully enough, despite my thorough research, I failed to notice the intel Arc GPU series heavily relies on resizable bar.

Resizable BAR / re-BAR / Smart Access Memory / Clever Access Memory, from what I gather - allows the CPU to access
the entire memory of the GPU instead of working with chunks of 256MB.

My current setup has a Ryzen 5 2600 and an A320 motherboard. Seems like both on the CPU and the Motherboard,
I am 1 generation short of supporting resizable bar.

Upon testing the Arc A750, I was notified multiple times that re-bar isn't enabled.
Trying a game like Overwatch 2 showed just how impactful it was.
For a CPU as old as mine, the Arc A750 immediately caused a CPU bottleneck (which was at 100%).

And thus, the performance was even worse than the GTX 1060, with noticeable mouse lag inputs, presumably because the PCU was busy trying
to keep up with the GPU and couldn't spare time to handle basic stuff like polling the mouse inputs.

According to this page, Intel states that (some) Ryzen 3000 series CPUs and Ryzen 500 series motherboards support re-bar.
Due to my bad experience in keeping my system upgradable, I wish to buy the cheapest CPU and motherboard combo to support re-bar.

So,

my question is:

Can anyone confirm whether any of the following AMD CPUs support resizable bar:

Ryzen 5 3500, Ryzen 3 3300X, Ryzen 5 4100 (4000 series does not appear on Intel's page for some reason)

I'm thinking of buying one of the three above and pair it with an A520 motherboard, like the GIGABYTE A520M K V2.

Specifically to enable resizable BAR for the Arc A750. If anyone heard of a similar setup working with re-BAR on,
it'll be great to know I can safely upgrade and fully utilize the GPU.

 

[KikeUY]

Hi. I do enjoy reading tpu , just made an account to tell op that I have the mobo mentioned (GIGABYTE A520M K V2) paired with a 5600g and a 5700xt and rebar(SAM on AMD) works just fine.
Little detail tho, after I did all the steps needed still no rebar. Found a thread on Reddit that you can solve it by going to the motherboard config and enable or disable network stack.
It looks like a completely unrelated option to rebar , but it did the magic.

 

[Dr. Dro]

Hi. I do enjoy reading tpu , just made an account to tell op that I have the mobo mentioned (GIGABYTE A520M K V2) paired with a 5600g and a 5700xt and rebar(SAM on AMD) works just fine.
Little detail tho, after I did all the steps needed still no rebar. Found a thread on Reddit that you can solve it by going to the motherboard config and enable or disable network stack.
It looks like a completely unrelated option to rebar , but it did the magic.

They would need to replace the processor as well, as A520 series does not support the 2600. The idea here is to just get ReBAR working at a moderate cost so they can use their A750 without issues, Intel Arc GPUs require Resizable BAR support or they will not perform adequately since there is no driver optimization for the standard 256 MB aperture.

B550 steel legend has it

Only Picasso APU is supported on 500 series chipset, Pinnacle Ridge is not. It would be cool if it worked, but since it is not on the list (and AMD claims it is not supported), I would not put money on it

ASRock B550 Steel Legend

Supports AMD AM4 Socket Ryzen™ 3000, 3000 G-Series, 4000 G-Series, 5000 and 5000 G-Series Desktop Processors<span style=color:red;>*</span>; 14 Power Phase Design, Digi Power, Dr. MOS; Supports DDR4 4733+ (OC); 1 PCIe 4.0 x16, 1 PCIe 3.0 x16, 2 PCIe 3.0 x1, 1 M.2 Key E for WiFi; Graphics Output...

www.asrock.com

Slightly older chart, 4000 has become 5000 and since then 300 and 400 got full support for newer CPUs, but the newer chipsets didn't get full support for older CPUs

AMD Releases the A520 Chipset: For Ryzen on a Budget

www.anandtech.com

 

[SamSegal]

Hi, I'm closing this thread (even though I'm not sure how?)

Special thanks to @Dr. Dro for alerting me to the incompatibility of the motherboard upgrade I had originally chosen.
And to anyone else who shared a useful insight in this upgrade journey.

I have succesfuly upgraded to the ASUS Prime B450M-A to utilize Resizable BAR with my Arc A750 GPU.
The results are even better than I expected, just ran Unigine Superposition Benchmark for now, but even with benchmark bias, this is impressive:

The Arc A750 performs better than twice than the dated GTX 1060 6G I had before.
Even with the 90$ motherboard upgrade, this is a hefty performance gain for a decent value.
Fingers crossed I will be able to resell both the GPU and the motherboard for an even better total upgrade value.

One major issue I had with upgrading the motherboard on my AMD AM4 platform:
After upgrading the motherboard to B450 from A320, I had this error shown "reboot and select proper boot device" when trying to boot.
It took me hours of messing around in the BIOS and trying to understand what went wrong.

Nothing worked until.. I plugged all of my HDDs as well. The Windows is installed on my SSD (using UEFI).
But when I connected just the SSD (via the M.2 connector), even when it showed in the BIOS - booting into it kept showing that error message.

Only after I connected all of my hard drives is when I suddenly managed to boot into Windows. Not sure why this happened,
but it took me a few good hours yesterday to get over it by "giving up and connecting everything anyway".

I guess the paradigm of connecting the minimum things to check the boot is fine is false sometimes.
From now on, I'll connect everything and even close the case covers and only debug if something isn't working.

Regardless, I'm glad how things turned out, we had some bumps on the road, but I didn't have to buy a lot more than just the GPU for the upgrade,
which wraps this current PC upgrade journey