topic Re: arc discrete rebar not working over tbt in Intel® Arc™ Discrete Graphics

arc discrete rebar not working over tbt

WindWind — Tue, 24 Jun 2025 00:09:39 GMT

just got my b580 and put it inside my egpu enclosure, which was then connected to my laptop via thunderbolt 3. everything works aside from the resizable bar, and absence of that apparently leads to a serious performance degradation, compared with how amd/nvidia gpus perform over thunderbolt.

i have enabled rebar in my bios, and it seems that my laptop firmware (lenovo 16irh8, with i9 13900H) has been preventing my driver from resizing the bar from a standard 256M to 16G.

you intel engineers should really look into this, since rebar is becoming increasingly popular nowadays and this lack of rebar support doesn't seem uncommon among other laptops with newer intel processors (i suspect it's an issue lying in your own standards of thunderbolt)

Re: arc discrete rebar not working over tbt

JeanetteC_Intel — Wed, 25 Jun 2025 07:41:42 GMT

Hello WindWind,

Thank you for posting in Intel Communities.

I appreciate you sharing your experience with the B580 in your eGPU enclosure connected through Thunderbolt 3. I understand the importance of Resizable BAR for optimal performance, and it's concerning that you're facing issues despite enabling it in the BIOS.

Given that your laptop's firmware might be restricting the Resizable BAR functionality, I recommend checking for any available firmware updates from Lenovo that might address this issue. Additionally, it could be helpful to reach out to Lenovo support to see if they have any insights or solutions specific to your model.

I appreciate your feedback regarding the potential limitations with Thunderbolt standards and Resizable BAR support. However, I need to emphasize that Intel® Arc™ Discrete Graphics Cards are not intended to be used on eGPU configurations. Though it might work somewhat, this configuration is not officially supported.

Source: Intel® Arc™ Series Discrete Graphics Card Low Performance in EGPU...

I hope this information is helpful.

Best regards

JeanetteC.

Intel Customer Support Technician

Re:arc discrete rebar not working over tbt

JeanetteC_Intel — Sun, 29 Jun 2025 23:58:54 GMT

Hello WindWind,

Did you get a chance to review the previous post?

Please let us know if you have any questions.

Best regards

JeanetteC.

Intel Customer Support Technician

Re:arc discrete rebar not working over tbt

JeanetteC_Intel — Thu, 03 Jul 2025 13:06:19 GMT

Hello WindWind,

Since I haven't received any response from you recently, I will go ahead and close this thread. If you require help in the future, please submit a new inquiry, as this thread will no longer be monitored.

Sincerely,

JeanetteC.

Intel Customer Support Technician