Arc A770 Loses Up to 24 Percent Performance Without Resizable Bar

Intel Arc A770 Limited Edition
Intel Arc A770 Limited Edition (Image credit: Intel)

Intel has revitalized the midrange graphics card market with the company's latest Arc A770, which will make its way into the list of best graphics cards. Starting at $329, the Arc Alchemist graphics card brings GeForce RTX 3060-like performance to the table with Resizable BAR (ReBAR) enabled, of course. But, without ReBAR or similar technology like Smart Access Memory (SAM), it's another story.

With Arc, Intel recommends potential consumers make sure their systems support ReBAR or SAM. The chipmaker has been very open about it and publishes it on its website (opens in new tab). ReBAR isn't mandatory but recommended since the chipmaker built its graphics cards and drivers around ReBAR. Intel fellow Thomas A. Peterson (TAP) said, "If you have an older PC without ReBAR support, just buy an RTX 3060, don't bother with Arc." Therefore, it's safe to assume that Arc graphics cards suffer a performance penalty on systems that lack support for ReBAR. Media news outlet TechPowerUp (opens in new tab) has tested the Arc A770 with ReBAR disabled, and the results speak for themselves.

Without ReBAR, the Arc A770's performance, on average, plummeted to 77% at 1080p (1920x1080), 76% at 1440p (2560x1440), and 80% at 4K (3840x2160). Arc owners who don't have a system with ReBAR are essentially losing almost a quarter of the performance from their graphics cards. Intel's other Arc offerings, such as the A750 and A380, will also undergo performance losses. However, we don't know to what degree.

Nonetheless, TechPowerUp's results don't paint the entire picture. The publication noted that the games suffered from stutters and were simply unplayable without ReBAR. Moreover, the lack of ReBAR significantly impacted the Arc A770 across 25 titles, so it's not just AMD- or Nvidia-specific titles.

In addition to testing ReBAR, TechPowerUp also evaluated whether the speed of the expansion slot impacts the Arc A770's performance. As a reminder, the Arc A770 comes with a conventional PCIe 4.0 x16 interface. However, the tests revealed that PCIe 3.0 is still plenty for the Arc A770 as long as ReBAR is enabled. Furthermore, TechPowerUp only recorded a performance difference of up to 2% between PCIe 3.0 and PCIe 4.0, so ReBAR support is more important than the expansion slot.

Regarding ReBAR, only Intel 10th Generation Comet Lake, 11th Generation Rocket Lake, and 12th Generation Alder Lake processors support that feature. As for AMD, SAM support is only present on Ryzen 3000 Zen 2 chips and newer. So while Arc's performance looks attractive and priced fairly, its requirements effectively lock out users with older systems. Arc also demands Windows 10 20H2 or Windows 11 as the operating system, so Windows 7 users, who are reluctant to upgrade, are also out of the picture.

The Arc A770 will hit the retail market on October 12, starting at $329. If you plan to upgrade to Arc for gaming, ensure your system supports ReBAR or SAM. If not, you're better off picking up a Radeon RX 6650 XT for $285 or even the GeForce RTX 3060 at $369.

Zhiye Liu
RAM Reviewer and News Editor

Zhiye Liu is a Freelance News Writer at Tom’s Hardware US. Although he loves everything that’s hardware, he has a soft spot for CPUs, GPUs, and RAM.

  • Alvar "Miles" Udell
    Intel's site doesn't list support for Windows 7 nor 8, making 10 20H2 the minimum OS.
    Reply
  • escksu
    Hmm.... intersting...

    I am wondering if there is actually alot more performanc could be unlocked from this feature. Esp. with PCIE 4.0/5.0 since the CPU could write to graphics card RAM much faster.

    The performance loss from Arc shows that this feature could have a big impact on performance. Maybe we are seeing very minimal gains on AMD/Nvidia cards because the GPU is not designed to take advantage of this.
    Reply
  • The Historical Fidelity
    escksu said:
    Hmm.... intersting...

    I am wondering if there is actually alot more performanc could be unlocked from this feature. Esp. with PCIE 4.0/5.0 since the CPU could write to graphics card RAM much faster.

    The performance loss from Arc shows that this feature could have a big impact on performance. Maybe we are seeing very minimal gains on AMD/Nvidia cards because the GPU is not designed to take advantage of this.

    I was thinking that too. AMD and Nvidia’s designs are biased toward the normal 256 MB standard since they have been building their designs well before re-bar came about. Since re-bar was released with the pci-e 3 standard but has only just now been utilized by AMD to edge out a win against nvidia then nvidia scrambling to get it to work with their 3000 series, it stands to reason that rebar inclusion was not a design requirement. Since Intel has a fresh start designing a micro-architecture, it makes sense that they would make the arc design reliant upon the newest cpu-vram interface.
    Reply
  • jkflipflop98
    Alvar Miles Udell said:
    Intel's site doesn't list support for Windows 7 nor 8, making 10 20H2 the minimum OS.


    ....so?

    Steam's stats say 7 and 8 combined account for 3% share. 10 and 11 garner 96.69% of the Steam base. Which is currently 24M accounts.
    Reply
  • KyaraM
    jkflipflop98 said:
    ....so?

    Steam's stats say 7 and 8 combined account for 3% share. 10 and 11 garner 96.69% of the Steam base. Which is currently 24M accounts.
    Some people really love their old, long depricated OS...

    Windows 7 was great, but people really need to move on at one point. You also simply can't implement backwards compatibility until anno dacumal. That's a lot of work. People already complain about Intel drivers and say they should have done less and added features over time, and now they want OS backwards compatibility into the early 2000's? Come one, one or the other.

    (Edited for typos)
    Reply
  • The Historical Fidelity
    KyaraM said:
    Some people really love their old, lomg depricated OS...

    Windows 7 was great, but people really need to move on at one point. You also simply can't implemwnt backwards compatibility until anno dacumal. That's a lot of work. People already conplain about Intel drivers and say they should have done lwss and added features over tume, and now they want OS backwards compatibility into the early 2000's? Come one, one or the other.
    Where’s my Windows ME support Intel…Geez
    Reply
  • InvalidError
    ReBAR isn't a "technology like SAM", it is the generic PCI-SIG name of the PCI feature and SAM is nothing more than AMD's house rebrand, just like FreeSync is AMD's house-brand for its implementation of VESA's Adaptive Sync.
    Reply
  • eye4bear
    I am running an Intel 10th gen chip, however I also am running Linux (kernel 5.19 up to date), you know the forgotten step-child, no mention if these work on Linux?
    Reply
  • wifiburger
    it's not just older system as per the article
    rebar / sam requires dx12 / new vulkan

    So any dx11 or older API there's no rebar and will show performance loss unless Intel fixes this issue
    Reply
  • spongiemaster
    wifiburger said:
    it's not just older system as per the article
    rebar / sam requires dx12 / new vulkan

    So any dx11 or older API there's no rebar and will show performance loss unless Intel fixes this issue

    Why would you think this is an issue? One would have to think that Intel knew what they were doing all along and didn't just coincidently develop an architecture optimized for SAM.
    Reply