Board analysis

At the heart of Sapphire’s 5850 Toxic is without a doubt its vapor chamber cooler.

The cooler itself is very similar to what Sapphire used last year on the 5870 Toxic. The vapor chamber cooler is placed inside a copper baseplate, just like the 5870 Toxic. It rests directly above the GPU, drawing heat off the chip. This heat is then transferred into various wicks inside the vapor chamber.

There’s a vaporization wick, where heat from the GPU causes the liquid inside the vapor chamber to vaporize. This water vapor then moves through the vacuum until it hits the condensation wick. Here the water vapor condenses and forms back into a liquid (releasing the heat in the process); this liquid is then absorbed by the transportation wick by capillary action, where it’s then transported back to the vaporization wick and the process is repeated.

To keep the vapor chamber cool, Sapphire uses three copper heatpipes, these are attached directly to the vapor chamber. Any remaining heat from the vapor chamber is transferred to the heatpipes, which are massive in size.

This heatpipe+vapor chamber cooling combination can dissipate a large amount of heat, and needs to be cooled in order to prevent creating a huge hotspot on top of the GPU. To accomplish this Sapphire employs a dual-slot aluminum heatsink+fan unit. The fan Sapphire uses is a 2-ball bearing unit, rather than sleeve bearings. Ball bearing fans tend to be more expensive than sleeve bearing fans, but they tend to generate less noise and are also more durable. In operation the 5850 Toxic generates so little noise that we couldn’t get a reading from a distance of 6” with our Extech sound level meter (our meter can read down to 40dB).


The cooler is encased inside a stylish plastic duct. Here we should note that the duct isn’t completely enclosed – there are multiple gaps for heat to escape. As such, not all the hot air from the GPU is exhausted out the back of your system case. In fact, more hot air probably escapes out the sides and back of the card than is exhausted outside the case, so you will want to plan accordingly and ensure the inside of your case is adequately ventilated with good airflow near the graphics card.

Duct is not fully enclosed

Hot air also escapes here...

...And especially here

To make room for the vapor chamber cooler, Sapphire uses a 10.1” PCB on the 5850 Toxic. This is a little longer than ATI’s reference design for the 5850, which measures in at 9.5”, but far shorter than NVIDIA’s GeForce GTX 285, which is 10.5” long in stock form.

OC’ed Speeds

Like all Toxic boards, Sapphire overclocks the 5850 Toxic from the factory. While the Radeon 5850 runs at 725MHz core/1000MHz memory in stock form, Sapphire’s Toxic 5850 is clocked at 765MHz core/1125MHz memory. This is an improvement of 5% and 11% on the graphics core and memory and makes the board one of the fastest 5850 cards on the market in terms of clock speeds.