SAPPHIRE Toxic RX 6900 XT Limited Edition Review

1. Introduction2. Sapphire Toxic RX 6900 XT3. Testing Methodology4. 3DMark Fire Strike & Time Spy5. 3DMark DirectX Raytracing6. Borderlands 37. Control8. Death Stranding9. The Division 210. F1 202011. Far Cry New Dawn12. Gears 513. Ghost Recon: Breakpoint14. Metro Exodus15. Middle Earth: Shadow of War16. Red Dead Redemption 217. Shadow of the Tomb Raider18. Total War Saga: Troy19. Watch Dogs: Legion20. Clock Speed21. Temperatures22. Acoustics23. Noise-Normalised Temperatures24. Power Consumption25. Overclocking26. Closing Thoughts27. View All Pages

It's been some years since we last looked at a graphics card from Sapphire's Toxic brand, but that changes today. Toxic is back, and it's back with a bang, as we review the RX 6900 XT Toxic Limited Edition, featuring a 360mm all-in-one liquid cooler. Sapphire claims this is the fastest RX 6900 XT on the market, with a rated boost clock of 2660MHz when using the card's ‘Toxic Boost' mode. Let's see if that claim holds true.

As far as I can tell, the last Sapphire Toxic graphics card to hit the market was the R9 390, all the way back in May 2016, so it's been almost five years without a proper flagship card from Sapphire. The Toxic RX 6900 XT Limited Edition is the first Toxic card to come with an integrated all-in-one liquid cooling solution which cools the GPU, while a fan and two heatpipes deal with the VRM and memory.

With its Toxic brand geared for all-out performance, Sapphire has also implemented what it calls ‘Toxic Boost', a one-click overclock which is accessible via the TriXX software. This raises the GPU's boost clock from 2365MHz up to 2660MHz, bumps up power draw to 400W total board power and also increases memory speeds by 0.8Gbps.

There's also the choice between the Performance and Quiet BIOS, plenty of RGB lighting as well as a beefed-up PCB compared to reference. Let's see what this card is really about.

	RX 6900 XT	RX 6800 XT	RX 6800	RX 5700 XT	RX 5700
Architecture	RDNA 2	RDNA 2	RDNA 2	RDNA	RDNA
Manufacturing Process	7nm	7nm	7nm	7nm	7nm
Transistor Count	26.8 billion	26.8 billion	26.8 billion	10.3 billion	10.3 billion
Die Size	519 mm²	519 mm²	519 mm²	251 mm²	251mm²
Ray Accelerators	80	72	60	n/a	n/a
Compute Units	80	72	60	40	36
Stream Processors	5120	4608	3840	2560	2304
Game GPU Clock	Up to 2015MHz	Up to 2015MHz	Up to 1815MHz	Up to 1755MHz	Up to 1625MHz
Boost GPU Clock	Up to 2250MHz	Up to 2250MHz	Up to 2105MHz	Up to 1905MHz	Up to 1725MHz
Peak SP Performance	Up to 23.04 TFLOPS	Up to 20.74 TFLOPS	Up to 16.17 TFLOPS	Up to 9.75 TFLOPS	Up to 7.95 TFLOPS
Peak Half Precision Performance	Up to 46.08 TFLOPS	Up to 41.47 TFLOPS	Up to 32.33 TFLOPS	Up to 19.5 TFLOPS	Up to 15.9 TFLOPS
Peak Texture Fill-Rate	Up to 720 GT/s	Up to 648.0 GT/s	Up to 505.2 GT/s	Up to 304.8 GT/s	Up to 248.4 GT/s
ROPs	128	128	96	64	64
Peak Pixel Fill-Rate	Up to 288.0 GP/s	Up to 288.0 GP/s	Up to 202.1 GP/s	Up to 121.9 GP/s	Up to 110.4 GP/s
AMD Infinity Cache	128MB	128MB	128MB	n/a	n/a
Memory	16GB GDDR6	16GB GDDR6	16GB GDDR6	8GB GDDR6	8GB GDDR6
Memory Bandwidth	512 GB/s	512 GB/s	512 GB/s	448 GB/s	448 GB/s
Memory Interface	256-bit	256-bit	256-bit	256-bit	256-bit
Board Power	300W	300W	250W	225W	185W

The make-up of the RX 6900 XT GPU has many similarities to the RX 6800 XT. Still fabricated on TSMC’s 7nm process node, it uses the same Navi 21 GPU, measuring 519 mm². The key difference is that the RX 6900 XT silicon is fully populated, with 80 Compute Units (CUs) compared to 72 for the 6800 XT. This means the flagship chip has an extra 512 Stream Processors, giving a grand total of 5120 shaders.

Rated clock speed is also identical between these two RDNA 2 GPUs. Reference RX 6900 XT has a rated game clock of 2015MHz and a rated boost clock of up to 2250MHz, but Sapphire has pushed the rated boost clock up to 2365MHz for the Performance BIOS. Enabling Toxic Boost sees this increase by almost 300MHz, to 2660MHz.

AMD has also increased the memory capacity, with 16GB of GDDR6 memory found on every RX 6000 SKU (so far). The memory is clocked at 16Gbps (or 16.8Gbps using Toxic Boost), and operates over a 256-bit memory interface for total bandwidth of 512 GB/s. However, AMD has also implemented a 128MB Infinity Cache on the Navi 21 GPU, to significantly increase effective memory bandwidth without excess power draw.

Speaking of power, the reference RX 6900 XT has a rated total board power (TBP) of 300W. Sapphire has increased this for both the Quiet and Performance BIOS, to 350W and 360W respectively, but we look at power draw in more detail later on in the review.

Become a Patron!