XFX Speedster Merc 308 Radeon RX 6600 XT review: It does one thing very well
Zoom zoom—if you're on the right racetrack.
By Brad Chacos
PCWorldAug 11, 2021 6:00 am PDT
Image: Brad Chacos/IDG
At a Glance
Excellent fast 1080p gaming
XFX design is cool, quiet, and attractive
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
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.
Best Prices Today: Speedster Merc 308 Radeon RX 6600 XT
Price comparison from over 24,000 stores worldwide
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.
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:
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.
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.
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!
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.
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
Our test system
Our AMD Ryzen 5000-series test rig can benchmark the effect of PCIe 4.0 support on modern GPUs, as well as the performance-boosting AMD Smart Access Memory and Nvidia Resizable BAR features (which are both based on the same underlying PCIe standard). Currently, we’re testing it on an open bench with AMD’s Wraith Max air cooler; in the future, we’ll add an NZXT Kraken liquid cooler to the mix. Most of the hardware was provided by the manufacturers, but we purchased the storage ourselves.
We’re comparing the $419 XFX Speedster Merc 308 Radeon RX 6600 XT against the various cards it’s replacing, either spiritually or practically: The $279 Radeon RX 5600 XT, the $350 Radeon RX 5700, and the $400 Radeon RX 5700 XT, as well as Asus’s spin on this GPU, the $550 ROG Strix RX 6600 XT. On the Nvidia front, we’ve included results for the reference-spec’d $330 EVGA RTX 3060 XC Black Gaming as well as EVGA’s fearsome GeForce RTX 3060 Ti FTW3 Ultra, because this card hovers in the same general price range as the Ti models.
All of these suggested prices are a fraction of what you’ll pay for these GPUs in the real world right now, of course, but using suggested pricing helps evaluate graphics cards as they were intended.
We test a variety of games spanning various engines, genres, vendor sponsorships (Nvidia, AMD, and Intel), and graphics APIs (DirectX 11, DX12, and Vulkan). Each game is tested using its in-game benchmark at the highest possible graphics presets unless otherwise noted, with VSync, frame rate caps, real-time ray tracing or DLSS effects, and FreeSync/G-Sync disabled, along with any other vendor-specific technologies like FidelityFX tools or Nvidia Reflex. We’ve also enabled temporal anti-aliasing (TAA) to push these cards to their limits. We run each benchmark at least three times and list the average result for each test.
Be sure to check out our original Radeon RX 6600 XT review for much deeper conversation about the GPU’s technical prowess and capabilities. We’ll be presenting the data without comment here until the end of the review.
Gaming performance benchmarks
Watch Dogs: Legion
Watch Dogs: Legion is one of the first games to debut on next-gen consoles. Ubisoft upgraded its Disrupt engine to include cutting-edge features like real-time ray tracing and Nvidia’s DLSS. We disable those effects for this testing, but Legion remains a strenuous game even on high-end hardware with its optional high-resolution texture pack installed. The game allocates more than 8GB of memory even at 1440p. Oof.
Horizon Zero Dawn
Yep, PlayStation exclusives are coming to the PC now. Horizon Zero Dawn runs on Guerrilla Games’ Decima engine, the same engine that powers Death Stranding.
Next page: gaming benchmarks continue
Gears Tactics puts it own brutal, fast-paced spin on the XCOM-like genre. This Unreal Engine 4-powered game was built from the ground up for DirectX 12, and we love being able to work a tactics-style game into our benchmarking suite. Better yet, the game comes with a plethora of graphics options for PC snobs. More games should devote such loving care to explaining what flipping all these visual knobs mean.
You can’t use the presets to benchmark Gears Tactics, as it intelligently scales to work best on your installed hardware, meaning that “Ultra” on one graphics card can load different settings than “Ultra” on a weaker card. We manually set all options to their highest possible settings.
Wolfenstein: Youngblood is more fun when you can play cooperatively with a buddy, but it’s a fearless experiment—and an absolute technical showcase. Running on the Vulkan API, Youngblood achieves blistering frame rates, and it supports all sorts of cutting-edge technologies like ray tracing, DLSS 2.0, HDR, GPU culling, asynchronous computing, and Nvidia’s Content Adaptive Shading. The game includes a built-in benchmark with two different scenes; we tested Riverside.
One of the best games of 2019, Metro Exodus remains one of the best-looking games around, too. The latest version of the 4A Engine provides incredibly luscious, ultra-detailed visuals, with one of the most stunning real-time ray tracing implementations released yet. The Extreme graphics preset we benchmark can melt even the most powerful modern hardware, as you’ll see below, though the game’s Ultra and High presets still look good at much higher frame rates.
We test in DirectX 12 mode with ray tracing, Hairworks, and DLSS disabled.
Borderlands is back! Gearbox’s game defaults to DX12, so we do as well. It gives us a glimpse at the ultra-popular Unreal Engine 4’s performance in a traditional shooter. This game tends to favor AMD hardware.
Strange Brigade is a cooperative third-person shooter where a team of adventurers blasts through hordes of mythological enemies. It’s a technological showcase, built around the next-gen Vulkan and DirectX 12 technologies and infused with features like HDR support and the ability to toggle asynchronous compute on and off. It uses Rebellion’s custom Azure engine. We test using the Vulkan renderer, which is faster than DX12.
Next page: gaming benchmarks continue
Total War: Troy
The latest game in the popular Total War saga, Troy was given away free for its first 24 hours on the Epic Games Store, moving over 7.5 million copies before it went on proper sale. Total War: Troy is built using a modified version of the Total War: Warhammer 2 engine, and this DX11 title looks stunning for a turn-based strategy game. We test the more intensive battle benchmark.
The latest in a long line of successful racing games, F1 2020 is a gem to test, supplying a wide array of both graphical and benchmarking options, making it a much more reliable (and fun) option that the Forza series. It’s built on the latest version of Codemasters’ buttery-smooth Ego game engine, complete with support for DX12 and Nvidia’s DLSS technology. We test two laps on the Australia course, with clear skies on and DLSS off.
Shadow of the Tomb Raider
Shadow of the Tomb Raider concludes the reboot trilogy, and it’s still utterly gorgeous a couple of years after its debut. Square Enix optimized this game for DX12 and recommends DX11 only if you’re using older hardware or Windows 7, so we test with DX12. Shadow of the Tomb Raider uses an enhanced version of the Foundation engine that also powered Rise of the Tomb Raider and includes optional real-time ray tracing and DLSS features.
Rainbow Six Siege
Rainbow Six Siege still dominates the Steam charts years after its launch, and Ubisoft supports it with frequent updates and events. The developers have poured a ton of work into the game’s AnvilNext engine over the years, eventually rolling out a Vulkan version of the game that we use to test. By default, the game lowers the render scaling to increase frame rates, but we set it to 100 percent to benchmark native rendering performance on graphics cards. Even still, frame rates soar.
Next page: Power, thermals, and conclusion
Power draw, thermals, and noise
We test power draw by looping the F1 2020 benchmark at 4K for about 20 minutes after we’ve benchmarked everything else and noting the highest reading on our Watts Up Pro meter, which measures the power consumption of our entire test system. The initial part of the race, where all competing cars are onscreen simultaneously, tends to be the most demanding portion.
This isn’t a worst-case test; this is a GPU-bound game running at a GPU-bound resolution to gauge performance when the graphics card is sweating hard. If you’re playing a game that also hammers the CPU, you could see higher overall system power draws. Consider yourself warned.
The Radeon RX 6600 XT draws less much power than the GeForce RTX 3060 (and RX 5600 XT) despite being tangibly faster, even with the XFX Merc 308’s factory overclock. Unsurprisingly, it uses the same amount of power as the Asus ROG Strix model.
We test thermals by leaving GPU-Z open during the F1 2020 power draw test, noting the highest maximum temperature at the end.
The XFX Merc 308 can’t come close to the ROG Strix’s frigid temperatures. But this card runs quieter and is plenty cool enough—especially when you consider the Asus card costs $130 more and doesn’t offer a tangible frame rate improvement. XFX’s streak of impressive cooling designs continues.
Should you buy the XFX Speedster Merc 308 Radeon RX 6600 XT?
As I said in my initial Radeon RX 6600 XT review, most people should be avoiding buying a graphics card right now. Prices remain insane while we suffer through a global chip shortage. In a vacuum, paying $420 for a graphics card finely tuned for 1080p gaming—high refresh-rate 1080p gaming, sure, but still 1080p gaming—feels absolutely outlandish. That goes doubly so considering that the much faster GeForce RTX 3060 Ti costs only $20 more than the 6600 XT’s $379 baseline price tag.
But we’re still living in interesting times. The GeForce RTX 3060 that this card handily bests is selling for $700 or more when you can find it, despite ostensibly being a $330 GPU. The RTX 3060 Ti is selling for $800 to $1,000 on Ebay right now. AMD’s counterpunch will no doubt cost an arm and a leg once it hits the streets, too.
If you can stomach the prices of today’s world, and you have a high refresh-rate 1080p monitor, the XFX Merc 308 Radeon RX 6600 XT is an excellent option, delivering fantastic HD performance in a quiet, cool, and cool-looking package. Look elsewhere if you have a 60Hz 1080p monitor though, or if you want to play at 1440p resolution. The 6600 XT does each well enough, but there are better GPUs available for those scenarios.
The XFX Merc 308 Radeon RX 6600 XT does just one thing—ultra-fast 1080p gaming—but it does it very, very well. And it does it for a whole lot cheaper than the ROG Strix…while still probably being too expensive for most people’s tastes.
Best Prices Today: Speedster Merc 308 Radeon RX 6600 XT