GPUs Graphics Reviews

Sapphire Radeon RX 6900XT Toxic Review – is AMD’s battle bolide with all-in-one water cooling really better than the Nitro+?

As a customer and connoisseur, one associates the Toxic with the most toxic and fastest variant of a graphics card series from Sapphire. There have been quite a few highly interesting graphics cards in history, which meanwhile already enjoy cult status and are true collector’s items. And then came Big Navi, 2021 and the Sapphire RX 6900XT Toxic. Fast is this card also, but it is a water-cooled variant, on which the tastes will probably divide. But I don’t want to get ahead of the test, because there are of course many superlatives and technical details that are really worth writing about.

With the (Attention! Officially mandated name) – SAPPHIRE TOXIC AMD Radeon™ RX 6900 XT Gaming Graphics Card with 16GB GDDR6, AMD RDNA™ 2. For simplicity’s sake, I’ll call it Sapphire Radeon RX 6900 XT Toxic again in the article, otherwise the charts and legends would explode, so here’s a particularly fast (and thus slightly thirstier) RDNA2 specimen on my table of good deeds, just waiting to be looked at in more detail as well. This sentence is not new and also fits into every review of a Big Navi graphics card.


But let’s unpack the whole thing first and be surprised, because the outer packaging is downright huge and the content is also sufficiently advertised with pretty aggressive graphics. If you open the lid of the inner box, you can already see the graphics card, the 360 mm radiator with three 120 mm fans and a set of interesting mini bits as a bonus. In addition, there is a bag with short screws for mounting the radiator and a DVD with quick start guide.

Sapphire has really packed a 360 mm slim radiator on this card and the inclined buyer will surely ask himself very quickly, how and where he should install the part optimally, if there is already an AiO compact water cooling for the high-end CPU in the computer or a fat tower cooler was installed. Because either both compact coolers collide or the CPU air cooler gets snapped. I’ll also go into more detail about this cooling solution in a moment, but this is actually a question you have to ask yourself before you buy. 

Because the installation length of the radiator is with scarce. 40 cm enormous and especially the rigid lead-out of the connections at the radiator should make an installation in the top of many cases significantly more difficult. In most cases only the front would remain, but then you have it blowing out and the rest of the PC doesn’t get any fresh air blown in. If blowing in, then you would have to unscrew the whole fans and rotate the radiator, but that might not be so easy due to the quite short cables of the fans (PWM, RGB).

With an RRP for the Sapphire RX 6900 XT Toxic of 1499 USD (1599 Euro) you already have a decent board on the counter.

Optics and haptics

The Sapphire Radeon RX 6900 XT Toxic weighs 1147 grams without radiator (2043 grams complete) and is thus clearly lighter than the reference card. It’s shorter than the reference at 27 cm, and a whopping 12 cm tall and 3.8 cm thick (dual-slot design) without the tubing, with a backplate and PCB adding a total of four more millimeters. The body is made of metallic looking plastic, the Sapphire lettering on the top behind a mirrored surface is aRGB illuminated, as is the mirrored and light metal appliqué insert on the front of this cover.

The colorful power of the LEDs also extends to the backplate as a nice backlight. 

Whereby one must still lose a word to the height. Again, there are only the two very rigid hoses coming straight out. If you then bend the whole thing, you need about 17 cm distance between the upper edge of the PEG and the side wall of the case! Otherwise, there will inevitably be pressure points. The whole pixel firework including illumination is supplied via two standard 8-pin sockets and a 6-pin socket connected in parallel to the second 8-pin socket.

The slot bracket is closed, carries 1x HDMI 2.1 and three instead of two DP ports. However, the USB Type C port is missing for this. More about the construction, the cooler and the assembly on the next page in the teardown.

Technology, dual BIOS and a software switch

With the 80 compute units (CU), the RX 6900 XT has 5120 shaders. The base clock of both BIOS versions is specified with 2135 MHz and the boost clock with 2365 MHz. The card uses 16 GB GDDR6 at 16 Gbps, which is made up of 8 modules of 2 GB each. This includes the 256-bit memory interface and the 128MB Infinity Cache, which is supposed to solve the bandwidth problem.

This graphics card copes with the new video codec AV1, they also support DirectX 12 Ultimate for the first time and thus also DirectX Raytracing (DXR). With AMD FidelityFX, they also offer a feature that should also give developers more leeway in choosing effects. Also included is Variable Rate Shading (VRS), which can save immense amounts of processing power by smartly reducing the display quality of areas of the image that are not in the player’s eye anyway. So much for the feature set of all new Radeon cards.

The Sapphire card has again the already known three-stage BIOS switch, which offers two BIOS versions and in the default position (3) even offers a BIOS change via software. The whole thing is solved with a small controller IC on the board.

The two screenshots from the MorePowerTool (MPT) first give information about the key data of the two BIOSes for the TGP – on the left you see the Performance BIOS (Primary), on the right the Silent BIOS (Secondary). Here, the allowed power consumption for the GPU and the corresponding supply voltages including the VRAM differs to the usual 289 watts, the “Silent” BIOS gets by with 8 watts less. The difference is so marginal that I don’t even include it anymore. Bottom line, the whole thing isn’t silent either because the pump…. But I don’t want to spoil it now.


But what are the other, equally important differences between the two BIOS variants? Now the fan speeds and the maximum targeted temperatures come into play. The Secondary BIOS already suggests a somewhat quieter performance here, as illustrated by the “Fan Acoustic Limit”. But in reality, the fans aren’t the only thing you hear. Here, too, Sapphire has lost some of its courage. Or at least they would have provided better fans and then slowed it down a bit more. Thus, however, the specifications have also been designed somewhat too restrained.


Raytracing / DXR

At the latest since the presentation of the new Radeon cards it is clear that AMD will also support ray tracing. Here one goes a way clearly deviating to NVIDIA and implements a so-called “Ray Accelerator” per Compute Unit (CU). Since the Radeon RX 6800 has a total of 72 CUs, this also results in 72 such accelerators for the Radeon RX 6800XT, while the smaller Radeon RX 6800 still has 60. A GeForce RTX 3080 comes with 68 RT cores, which is nominally less for now. When comparing the smaller cards, the score is 62 for the RX 6800 and 46 for the GeForce RTX 3070. However, RT cores are organized differently and we will have to wait and see what quantity can do against specialization here. So in the end it’s an apples and oranges comparison for now.

But what has AMD come up with here? Each of these accelerators is first capable of simultaneously computing up to 4 beam/box intersections or a single beam/triangle intersection per cycle. This way, the intersection points of the rays with the scene geometry are calculated (analogous to the Bounding Volume Hierarchy), first pre-sorted and then this information is returned to the shaders for further processing within the scene or the final shading result is output. NVIDIA’s RT cores, however, seem to have a much more complex approach to this, as I explained in detail during the Turing launch. What counts is the result alone, and that’s exactly what we have suitable benchmarks for.

Smart Access Memory (SAM)

AMD already showed SAM, i.e. Smart Access Memory, at the presentation of the new Radeon cards – a feature I enabled today in addition to the normal benchmarks, which also allows a direct comparison. But actually SAM is not Neuers, just verbally more nicely packaged. This is nothing else than the clever handling of the Base Address Register (BAR) and exactly this support must be activated in the substructure. With modern AMD graphics hardware, resizable PCI bars (see also PCI SIG from 4/24/2008) have played an important role for quite some time, since the actual PCI BARs are normally only limited to 256 MB, while with the new Radeon graphics cards you can now find up to 16 GB VRAM.

The result is that only a fraction of the VRAM is directly accessible to the CPU, which without SAM requires a whole series of workarounds in the so-called driver stack. Of course, this always costs performance and should therefore be avoided. So that’s where AMD comes in with SAM. This is not new, but it must be implemented cleanly in the UEFI and later also activated. This only works if the system is running in UEFI mode and CSM/Legacy are disabled.

CSM stands for the Compatibility Support Module. The Compatibility Support Module is exclusive to UEFI and ensures that older hardware and software will work with UEFI. The CSM is always helpful when not all hardware components are compatible with UEFI. Some older operating systems and the 32-bit versions of Windows also do not install on UEFI hardware. However, it is precisely this compatibility setting that often prevents the clean Windows variant required for the new AMD components from being installed.

First you have to check in the BIOS if UEFI or CSM/Legacy is active and if not, make sure to do this step. Only then you can activate and use the resizable PCI-BARs at all, but stop – does your Windows boot at all then? How to convert an (older) disk from MBR to GPT, so that it is recognized cleanly under UEFI, you could read among other things also in the forum, if there are questions in this regard, that leads here now too far.
The fact is that AMD sets the hurdles for the use of SAM quite high and has only communicated this sparsely so far. A current Zen3 CPU is required, as well as a B550 or X570 motherboard with an updated BIOS. Then again, the UEFI thing is a small but incredibly important side note. It should also be noted that NVIDIA and Intel have already announced their own solutions or plan to use them in the future. One goes first, the others follow suit, whereas one could have done it long ago. But they didn’t, for whatever reason. Over 12 years of drawer is plenty of wasted time. But better late than never.

Benchmarks and evaluation

For the benchmarks, I chose the same 10 games, analogous to the launch article, weighting between old and new, and AMD- or NVIDIA-specific. Since everything is very similar to the launch article of the Radeon cards, this time there is only a cumulative summary of all games with a detailed explanation for each resolution. The power consumption is also given in great detail, as you are used to.

Test system and evaluation software

The benchmark system completely relies on AMD. PCIe 4.0 is of course mandatory. This includes the matching X570 motherboard in the form of an MSI MEG X570 Godlike and the Ryzen 9 5950X, which is water-cooled and slightly overclocked. Add to that the matching DDR4 4000 RAM from Corsair in the form of the Vengeance RGB, as well as several fast NVMe SSDs. For direct logging during all games and applications, I use both NVIDIA’s PCAT and my own shunt measurement system, which adds to the convenience immensely. The measurement of the detailed power consumption and other somewhat more complicated things is carried out in the special laboratory on two tracks by means of high-resolution oscillograph technology…

…and the self-created MCU-based measurement setup for motherboards graphics cards (pictures below), where at the end in the air-conditioned room also the thermographic infrared images are created with a high-resolution industrial camera. The audio measurements are then done outside in my Chamber (room-within-a-room).

The software used relies on my own interpreter including evaluation software as well as a very extensive and flexible Excel sheet for the graphical implementation. I have also summarized the individual components of the test system in a table:

Test System and Equipment
AMD Ryzen 9 5950X OC
MSI MEG X570 Godlike
2x 16 GB Corsair DDR4 4000 Vengeance RGB Pro
1x 2 TByte Aorus (NVMe System SSD, PCIe Gen. 4)
1x 2 TB Corsair MP400 (Data)
1x Seagate FastSSD Portable USB-C
Be Quiet! Dark Power Pro 12 1200 Watt
Alphacool Eisblock XPX Pro
Alphacool Eiswolf Extreme (modified)
Alphacool Subzero
Raijintek Paean
Monitor: BenQ PD3220U
Power Consumption:
Oscilloscope-based system:
Non-contact direct current measurement on PCIe slot (riser card)
Non-contact direct current measurement at the external PCIe power supply
Direct voltage measurement at the respective connectors and at the power supply unit
2x Rohde & Schwarz HMO 3054, 500 MHz multichannel oscilloscope with memory function
4x Rohde & Schwarz HZO50, current clamp adapter (1 mA to 30 A, 100 KHz, DC)
4x Rohde & Schwarz HZ355, probe (10:1, 500 MHz)
1x Rohde & Schwarz HMC 8012, HiRes digital multimeter with memory function

MCU-based shunt measuring (own build, Powenetics software)
Up to 10 channels (max. 100 values per second)
Special riser card with shunts for the PCIe x16 Slot (PEG)

NVIDIA PCAT and FrameView 1.1

Thermal Imager:
1x Optris PI640 + 2x Xi400 Thermal Imagers
Pix Connect Software
Type K Class 1 thermal sensors (up to 4 channels)
NTI Audio M2211 (with calibration file)
Steinberg UR12 (with phantom power for the microphones)
Creative X7, Smaart v.7
Own anechoic chamber, 3.5 x 1.8 x 2.2 m (LxTxH)
Axial measurements, perpendicular to the centre of the sound source(s), measuring distance 50 cm
Noise emission in dBA (slow) as RTA measurement
Frequency spectrum as graphic
OS: Windows 10 Pro (all updates, current certified or press drivers)


Lade neue Kommentare


Senior Moderator

1,601 Kommentare 414 Likes

Das T-Shirt gefällt mir schon mal

Antwort Gefällt mir



1,771 Kommentare 453 Likes

Beeindruckend! Schöner Test.

Antwort Gefällt mir



441 Kommentare 211 Likes

Wie soll man in einem etwas schmälern Gehäuse eigentlich die Wasserschläuche biegen, wenn die doch relativ starr sein sollen ? Oder ist die Karte nur für Riser a´la NXZT Gehäuse gedacht ?

Antwort Gefällt mir



200 Kommentare 93 Likes

eine grafikkarte mit 360er wärmetauscher, ist ja ansich oki, wenn man ganz grob 120w je 'lüfter-länge' kalkuliert.
aber was zum henker soll dann, wenn ich schon einen riesen wärmetauscher dran hab, bitteschön der lüfter auf der grafikkarte?!

sieht für mich so aus als ob da ein entwickler alle möglichkeiten in einen topf geworfen hat, umgerührt und daraus ein produkt gemacht hat.
fehlt nurnoch ein peltier-element auf der GPU.......

Antwort 1 Like



441 Kommentare 211 Likes

Soll vielleicht im Desktop Betrieb möglichst leise sein und erst zum Gluckern anfangen, wenn die Karte richtig gefordert wird. Von einem "Zero Fan" Modus im Desktop Betrieb wie bei meiner Nvidia Karte hat Igor hier nix geschrieben oder ?

Antwort Gefällt mir



193 Kommentare 18 Likes

Warum wurde bei dem Test kein Max. OC getestet?

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Igor Wallossek


5,187 Kommentare 8,009 Likes

Steht beim Takt. Mehr geht kaum.

Antwort 2 Likes



3 Kommentare 0 Likes

Erstmal vielen Dank für das echt gute Review!

Wie hoch waren denn die Tempraturen bei den 396 Watt? Also Edge und "normal".

Antwort Gefällt mir



1 Kommentare 0 Likes

Ein Top Test, danke sehr.

Anliegender Durchschnittstakt/maximale Taktspitzen finde ich für diese Grafikkarte, bei dem Preis, enttäuschend.
Aufgewärmt und stabilisiert (+15 % mehr Strom) "bis zu 2600 MHz", bei den Temperaturen, heist es fand keine Vorselektion der Chips statt.

Bei der UVP (Händlerpreis dürften 2000 € sein) hätte ich ein Binning und die besten Chips erwartet.
Da schaffen sogar Amds Referenzkarten - falls in der Silicon-Lotterie gewonnen -, mit Wasser gekühlt, gerne 2700 - 2800 MHz durchschnittlich.
Bei dem Preis hätte es das Beste vom Besten sein müssen.

Antwort Gefällt mir

Igor Wallossek


5,187 Kommentare 8,009 Likes

2.800 schaffte hier bisher keine 6900XT unter Last. Übrigens skaliert die Performance ab 2650 MHz nicht mehr nach oben. Das Teil wird nur durstiger. Brechstange, aber ohne Sinn und Verstand. Binning wäre allerdings schön gewesen, da stimme ich Dir zu :(

Bei 40 Watt mehr ist die Karte immer noch bei ca. 53 Gead Edge, das ist schon ok. Das Delta zum Hotspot ändert sich ja deswegen nicht.

Antwort 3 Likes

Danke für die Spende

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About the author

Igor Wallossek

Editor-in-chief and name-giver of igor'sLAB as the content successor of Tom's Hardware Germany, whose license was returned in June 2019 in order to better meet the qualitative demands of web content and challenges of new media such as YouTube with its own channel.

Computer nerd since 1983, audio freak since 1979 and pretty much open to anything with a plug or battery for over 50 years.

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