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  • XFX Speedster Merc 308 Radeon RX 6600 XT

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It’s a mouthful, but the name “XFX Speedster Merc 308 Radeon RX 6600 XT Black Edition” really tells you everything you need to know about the company’s latest offering.

This graphics card represents the latest in a series of stunning XFX custom designs—which last wowed us in the form of the Radeon RX 6700 XT Merc 319—built around AMD’s new Radeon RX 6600 XT GPU, which offers spectacular 1080p performance on high refresh-rate displays. If that sounds like what you’re looking for, the XFX will make you very happy indeed, assuming you can stomach the high starting price of the Radeon RX 6600 XT while the world is in the midst of a crippling GPU shortage.

Fortunately, XFX doesn’t require your first-born child to buy the XFX Merc 308. The overclocked, custom-cooled card costs between $409 and $419 depending on the store, I’m told. That’s $30 to $40 more than the Radeon RX 6600 XT’s baseline price, which is reasonable for a kitted-out custom model like this. You’ve got options, though. If you’d prefer the same frame rates with less bling, XFX’s $399 Quick 308 strips out the flair (and RGB) you get in the Merc, marrying overclocked performance with a clean, black shroud. Finally, the company’s Swft 210 Core sticks to no-frills and reference specs for AMD’s suggested $379 pricing.

Today we’re digging into the flagship Merc 308. Let’s go.

XFX Speedster Merc 308 Radeon RX 6600 XT specs, price, and design

dsc01780 Brad Chacos/IDG

Be sure to read our initial Radeon RX 6600 XT review for a deeper look into the new GPU’s technical bits. We’ve included a refresher cheat sheet below, but basically, the Radeon RX 6600 XT is a full-fledged RDNA 2 GPU with all of the benefits that provides, from excellent power efficiency to sky-high clock speeds.

One tidbit worth noting: AMD tuned the 6600 XT’s Infinity Cache around 1080p gaming. If you bump the resolution up to 1440p, its performance falls off quite a bit. That’s because using Infinity Cache lets AMD use a smaller memory bus width for better power efficiency, but the GPU needs to send signals over that bus to the onboard GDDR6 memory more often at higher resolutions. The 6600 XT can game at 1440p, but it simply isn’t optimized for the task because of its tiny 128-bit bus and smaller Infinity Cache. If you have a 1440p display, opt for a GeForce RTX 3060 Ti instead.

With that out of the way, here’s that spec cheat sheet:

rx 6600 xt specs AMD

XFX juiced the Merc 308’s Navi 23 GPU a bit. While AMD’s reference spec targets a typical Game Clock of 2,359MHz, the Merc 308 ups that to 2,428MHz—a nice 69MHz boost. The 8GB of GDDR6 memory blazes along at the same 16Gbps as the reference spec. That’s plenty of speed and capacity for the 1080p gaming at which the Radeon RX 6600 XT excels.

The real draw is XFX’s custom cooling design, which looks killer and enables those ultra-fast clock speeds. The Merc 308 is built around a custom PCB with a 6+2 phase full-digital PWM power design. A nickel-plated copper plate connects to four 6mm heat pipes to draw performance-killing heat away from the GPU and GDDR6 memory modules, pulling it into the card’s large heat sink. (Warning for small case owners: The Merc 308 uses a long 2.5-slot design.) Three 80mm fans with nine blades apiece circulate cooler air through that heat sink, aided by a cut-out in the aluminum backplate that allows for better airflow.

dsc01757 Brad Chacos/IDG

That’s a whole lot of words to say that the XFX Speedster Merc 308 comes brimming with cooling technology that easily tames the overclocked Radeon RX 6600 XT GPU inside. This is a cool, silent graphics card. The Asus ROG Strix 6600 XT we tested in our initial review runs much cooler, but also somewhat more audibly, and it costs $130 more than the XFX model even before the inevitable real-world markup occurs. It’s also not tangibly faster than the XFX Merc 308, as you’ll see in our benchmark section.

The Merc 308 also includes the aforementioned bling, for which XFX charges a (slight) premium over the bling-less Swft model. While the Swft sticks to a plain black shroud, the Merc jazzes things up with chrome accents around the fans and the edges of the card, along with a spiffy illuminated logo on the edge. Refreshingly, you won’t find any RGB onboard the Merc.

dsc01725 Brad Chacos/IDG

Ooooo, pretty lights.

Here’s what we said about the fresh logo design when we first spotted it on the XFX Merc 319 6800 XT, and it still holds true for the 6600 XT version:

“The XFX and [Radeon RX 6600 XT] logos on the side are illuminated though, and in a surprisingly striking fashion. Their white lights (red, for the “RX” lettering) shine much more cleanly and clearly than the logos do on rival graphics cards—sort of like the difference between standard car headlights and LED headlights. These pictures don’t capture how nice it looks.”

That backplate still features a big, aggressively styled “Merc” logo, as you can see at the top of this page, but it’s done in black on the 6600 XT version, so it shouldn’t be as love-it-or-hate-it as the standout white letters on pricier Merc offerings. (I love it.) If you don’t like all these extras, opt for the plain black XFX Swft instead. Easy!

dsc01742 Brad Chacos/IDG

The BIOS switch lies to the right of the 8-pin power connector.

XFX equipped the Merc 308 with a dual-BIOS switch to aid in overclocking endeavors. Many custom graphics cards load each setting with different Performance and Quiet profiles, but the Merc 319 sticks to the same setup for each. Power comes via a single 8-pin connector, and the card comes with an HDMI 2.1 connection and three DisplayPorts.

dsc01744 Brad Chacos/IDG

Port report

Like other RX 6000-series GPUs, XFX’s take on the RX 6600 XT supports all of RDNA 2’s various features, including FidelityFX Super Resolution and Smart Access Memory to boost performance, real-time ray tracing capabilities, AV1 video decoding, DirectX 12 Ultimate goodies, an improved version of Radeon Boost that wraps in Variable Rate Shading, Radeon Anti-Lag across all major DX APIs, FreeSync display support, AMD Link streaming to other devices, and much more. AMD’s robust Radeon Settings app includes both manual and automatic performance tuning controls so you can tweak the card to your heart’s desire with those dual BIOS profiles.

Let’s get to benchmarking.

Next page: Our test system, benchmarks begin

  • XFX Speedster Merc 308 Radeon RX 6600 XT

    The Speedster Merc 308 combines a solid and attractive custom design with AMD’s Radeon RX 6600 XT, and XFX doesn’t charge an outrageous premium for its extras. Consider it if you want an ultra-fast 1080p gaming experience, but only if you have a high refresh-rate monitor.


    • Excellent fast 1080p gaming
    • Very power-efficient
    • XFX design is cool, quiet, and attractive
    • Dual-BIOS switch
    • AMD features like FSR, Radeon Boost, Smart Access Memory can make it faster


    • Very, very high MSRP for a 1080p card
    • 1440p performance isn’t as impressive due to memory setup
    • Ray tracing lags behind Nvidia’s performance