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XFX Radeon RX 6600 XT Speedster MERC 308 Review

Joseph Bradford Posted:
Hardware Reviews 0

Yesterday we took a look at AMD’s RX 6600 XT, a GPU option targeting high-refresh rate 1080p gaming. Today, we’re still looking at the RX 6600 XT, however this time it’s the XFX variant. The XFX RX 6600 XT Speedster Mercury 308 Black is one of the AIB options available to buyers today, as AMD isn’t releasing a reference board at the moment. With a retail price of $419, how does the Merc 308 Black stack up, and does it do enough to justify 1080p gaming at a premium?


  • Architecture: RDNA 2.0
  • Memory: 8GB GDDR6
  • Memory Bus: 128 bit
  • Memory Bandwidth: 256 GB/s
  • Base Clock: 2188 MHz
  • Game Clock: 2428 MHz
  • Boost Clock: 2607 MHz
  • Memory Clock: 16 Gbps
  • Shading Units: 2048
  • Texture Units: 128
  • ROPs: 64
  • Compute Unites: 32
  • RT Cores: 32
  • Infinity Cache: 32 MB
  • I/O: 1x HDMI 2.1; 3x DisplayPort 1.4
  • Maximum Digital Resolution: 7680 x 4320
  • Price: $419 Suggested Retail Price

First Impressions

Like I’ve said in pretty much every AMD card review so far, I really appreciate aggressive looking GPUs. The XFX Mercury 308, however, looks a bit more basic compared to the edgier style of the 6000 series reference cards, or even the over-the-top edges we see with the MSI variant we reviewed previously. I don’t dislike it, but it feels routine, reminding me of the THICC model I reviewed previously from XFX. It’s an iconic look that fits the XFX line well, even if I prefer more aggressive looking GPUs, personally.

I do appreciate the lighting around the logo on the side, while the backplate sports the Merc 308 logo as if it were spray-painted  by a top-notch graffiti artist. And while I feel the shroud around the chassis of the Merc 308 is a bit mundane, I do appreciate the silver trim accenting the edges and the fan wells.

XFX RX 6600 XT Speedster MERC 308

The Merc 308 sports three 80mm GPU fans to keep the card cool under pressure.  Additionally, the GPU and memory on the 308 are cooled using a nickel-plated copper plate which is connected using four 6mm heat pipes. The card is also designed to allow for maximum airflow through the card itself to help keep the Merc 308 cool.

Because the Merc 308 is an RX 6600 XT, it obviously takes advantage of all of the features that come with the RDNA 2 architecture like Radeon Chill, Anti-Lag to help those competitive gamers, Radeon Boost (on supported titles), as well as Radeon’s latest introduction to the FidelityFX suite of technologies, Super Resolution (FSR). I explained FSR more in detail in my previous 6600 XT review, which you can check out here if you’re interested.

While there is no reference 6600 XT available, we do have reference specs. The Merc 308 is a factory overclocked version of the reference 6600 XT, seeing an increase in all of its clock speeds, with its base clock seeing an increase from 1968MHz to 2188 MHz, as well as the Boost clock seeing an uptick from 2589 MHz to 2607 MHz. GPUs  today are smart enough to ramp up the boost clock when needed, and we noticed the clock speeds ramping up to a peak of 2628 MHz during our testing.

XFX RX 6600 XT Merc 308 Benchmarks

To benchmark the 6600 XT, we put it through its paces using a combination of synthetic and gaming tests, both regular rasterization as well as using hardware accelerated real-time ray tracing on supported titles.

Our test bench is identical to the one used in the previous 6600 XT review, and we’ve included both the AMD cards around the 6600 XT, including last generation’s 5700 XT, as well as the closest Nvidia competitors in the 3060 and the RTX 3060 Ti.

Test Bench 

  • CPU: Intel i7-10700K @ 3.8GHz (Boost Clock up to 5.1 GHz) 
  • Cooling: Corsair 100i 240mm Liquid Cooler 
  • Motherboard: Gigabyte Aorus Z490 Ultra 
  • RAM: Corsair Vengeance 32GB @ 3200MHz 
  • Storage: Intel 760p 2TB M.2 NVMe, ADATA Falcon 1TB M.2 NVMe 
  • PSU: RM 850X 850W 
  • Case: Lian Li 011 Dynamic 

As stated in our previous RX 6600 XT review, it is important to note that as we are using an Intel powered rig, we are unable to provide benchmarks for the RX 6600 XT if we were using AMD’s Smart Access Memory. We highly recommend reading other reviews would be able to provide this data to get a clearer picture, especially if this is something your rig is able to handle.  

XFX RX 6600 XT Merc 308 – Synthetic Benchmarks

For synthetic testing, we turned once again to 3DMark’s suite of DirectX 12 and 11 tests, Time Spy and FireStrike. As the RX 6600 XT is billed as a 1080p card, we opted for the basic versions of these tests versus their Ultra variants, and unless otherwise noted we used default settings.

As we can see in Time Spy, the XFX Merc 308 hangs in there with the MSI Gaming X 6600 XT, though the latter does pull ahead both in Overall and Graphics score. It is also consistent with what we see compared to last-gen’s 5700 XT beating both 6600 XT cards here across the board. Even though Nvidia’s RTX 3060 does lag behind the 6600 XT in the test, the $399 MSRP RTX 3060 Ti Founder’s Edition card pulls ahead of the 6600 XT by quite a bit.

In the DX11 FireStrike benchmark, we see similar results with the MSI 6600 XT pulling ahead of the XFX offering in all of the data points. The XFX RX 6600 XT Merc 308 does have a good showing against the 5700 XT, as well as hangs with the 3060. Though again, we see the 3060 Ti pull ahead of the AMD offering.

XFX RX 6600 XT Merc 308 – Gaming Benchmarks

For games, we opted to test a range of both APIs as well as game engines, from Watch Dogs Legion’s Anvil Next, to the beautiful Decima Engine powering Guerilla Games’ Horizon Zero Dawn. These benchmarks do reflect regular rasterization tests. We will have our ray tracing thoughts below. Unless otherwise stated, each test was run using the highest in-game preset for each title at both 1080p,  the target resolution for the 6600 XT, as well as 1440p.

When possible, our tests used an in-game benchmark tool to provide as consistent a canvas for the card to be put through its paces. The exception here is Remedy’s Control, which has no in-game tool. For its test, we ran through the notoriously demanding Corridor of Doom in a circuit, pushing the card as much as we could in the process. For Final Fantasy XIV, we utilized the Shadowbringers benchmark since the Endwalker test is too recent for us to be sure it’s as consistent as possible to include in this test. We will hopefully be confident in the results soon in order to include it in the future tests leading to its November release.

For Anno 1800, we test both native resolution as well as put AMD’s FidelityFX Super Resolution through its pacing. While Anno does not feature DirectX Ray Tracing, it does allow players to eke out some performance using FSR, so we ran the test using the Balanced preset aiming to see the quality of the technique in providing a near-native presentation while also providing a performance increase.

When comparing the two 6600 XT’s on offer, the results are almost identical in spots. The one major difference is Assassin’s Creed Valhalla, with the XFX 6600 XT seeing a 15% increase in performance over the MSI variant at 1080p. This result is more down to earth when testing 1440p in the title. The XFX card also holds an edge at 1080p in Watch Dogs, but it’s not as aggressive, clocking in at 67 FPS compared to the MSI’s 60 FPS average.

Compared to the 5700 XT, the XFX actually lags behind on average, seeing the MSI RX 5700 XT Gaming X eke out a (admittedly within the margin of error) 1% better performance. Compared to the competition, we see the XFX RX 6600 XT Merc 308 turn in 5% more performance on average compared to the EVGA RTX 3060 Black. However, when compared to the next card in Nvidia’s line-up, the RTX 3060 Ti, the Merc 308 is not exactly the most competitive. The  3060 Ti sees a 20% increase in performance at 1080p on average over the AMD card. This is accentuated in titles like Control which sees the 3060 Ti take the 6600 XT to task with a framerate average of 97 to 68, respectively, a whopping 42% increase over the AMD card.

XFX RX 6600 XT Merc 308 – Ray Tracing Benchmarks

For ray tracing, we start things off again with 3DMark’s synthetic testing suite bringing the Port Royal benchmark to bear. AMD’s 6000-series is the first for the company to include hardware acceleration for ray tracing. While the amount of RT cores the 6600 XT is pared down compared to its RDNA 2 siblings, it’s still possible to enable ray tracing on the card should in games that support the technology.

As with the rest of the 6000 series,  the 6600 XT lags behind Nvidia’s 30-series cards. These 30-series cards are the second generation of cards from Nvidia to include hardware acceleration for ray tracing. Even compared to the cheaper RTX 3060, the 6600 XT feels behind from the get go here.

When looking at gaming performance, that trend pretty much continues with the exception of Counterplay’s Godfall. The looter-slasher performs quite well on AMD’s cards, and as one of the few titles that includes both ray tracing and support for FidelityFX Super Resolution, it turns in some legitimately impressive numbers.

However, even here we see the Nvidia cards pull ahead, especially since FSR isn’t exclusive to AMD cards.The technology is platform agnostic and can also run on Nvidia’s cards. Even the cheaper RTX 3060 turns in higher results at 1080p with FSR Balanced selected, bringing in an uptick of 7% more performance.

When looking at other ray tracing applications, the RX 6600 XT feels hit or miss. Watch Dogs Legion and its extensive and expensive implementation of ray traced reflections is legitimately unplayable on AMD’s 6600 XT with ray tracing set to ultra, and even Control struggles to maintain a playable framerate. This is further hampered by the fact that most ray tracing-capable games don’t yet support FSR, while the vast number of those games  include Nvidia’s Deep Learning Super Sampling technique making many ray tracing-enabled games playable on Nvidia cards.

XFX RX 6600 XT Merc 308 – Thermals And Noise

Like the MSI RX 6600 XT Gaming X before it, the Merc 308 is legitimately quiet. It helps that the card never gets too hot, though even with three fans it does run a little higher than its MSI cousin.

While the numbers here are perfectly acceptable, the GPU never breaks 80 C, peaking at 77 C in Control. Even under load, though, the Merc 308 Black never sounded loud, its three fans spinning quietly to keep the card as cool as it can under load. It’s refreshing, as gamed without my headphones to test out the ambient noise and honestly my laptop on my desk was much louder running Microsoft Word (which might be cause for concern on my laptop, really). If you get this card and you’re concerned about noise, don’t be.

Final Thoughts And Conclusion

The XFX RX 6600 XT Mercury 308 Black is, objectively, not a bad card.  It performs the brief on the box, high refresh-rate 1080p gaming, and provides an entry path for some 1440p gaming. However, the RX 6600 XT suffers from a fatal flaw out of the gate: its price.

Forgetting for a second the current silicon shortage and increase in price to materials we’ve seen since the Covid-19 Pandemic began last year, , $419 is simply too high for 1080p gaming even in a perfect market where the majority of cards available will be at its retail price. This is pronounced when you consider the price compared to the retail prices of its nearest competitors. With a 27% increase in price over the Nvidia’s RTX 3060’s retail price of $329, the meager 5% more performance on average is a bit of a buzzkill. Additionally, considering the Founder’s Edition of the RTX 3060 Ti is competitively priced at $399, 4% cheaper with 20% more performance on average, it makes the RX 6600 XT feel very poorly positioned in the market.

This is, of course, assuming you can find any of these cards at their retail price.

Couple this with the fact that in ray tracing applications the RTX cards will have generally better performance and there is such a head start with DLSS,  AMD’s ray tracing and FSR-enabled offering feels less suited to excel in the future. This could change as more games adopt FSR, but right now the RX 6600 XT doesn’t feel positioned to really be a card that can sustain someone for the future.

The XFX RX 6600 XT Mercury 308 Black is objectively not a bad card. If you are looking for high-refresh rate 1080p gaming, it does that and then some. It’s a good-looking card as well, and will look good in your rig thanks to its sleek design and silver trim accentuating the curves of the card.

However, it’s really hard to recommend 1080p at such a premium price, especially as 1440p and 4K become more and more mainstream (and consoles nowadays can provide 4K experiences for just a little bit more upfront). The XFX RX 6600 XT Speedster Merc 308 Black isn’t a bad card. It’s just a hard one to recommend.

  • Stylish Design Accented By Striking Silver Trim
  • Easily provides high refresh rate 1080p Gaming
  • Can act as an entry point for 1440p
  • Doesn't do enough to stand out among competition
  • RT Performance is still left wanting
  • Overpriced for 1080p gaming, especially in 2021


Joseph Bradford

Joseph has been writing or podcasting about games in some form since about 2012. Having written for multiple major outlets such as IGN, Playboy, and more, Joseph started writing for MMORPG in 2015. When he's not writing or talking about games, you can typically find him hanging out with his 10-year old or playing Magic: The Gathering with his family. Also, don't get him started on why Balrogs *don't* have wings. You can find him on Twitter @LotrLore