Temperature Testing

Without a doubt, it looks like Sapphire’s vapor chamber technology is working like a charm to tame the heat of the overclocked RV670XT core. However, it should be noted that for the stock HD3870 we used the reference heatsink and the default fan speed profile which is absolutely horrible at cooling the core. We find that this kind of performance by a single slot cooler is absolutely incredible if you want a compact heatsink but it does come with some tradeoffs.


Here we have placed a temperature probe about 4” from the back of the heatsink exhaust to demonstrate a very clear point: this card dumps copious amounts of heat back into your case. Considering the ambient temperature of the room was hovering around 22 degrees, a delta of 21 degrees between the ambient temperature and the exhaust temperature is quite a bit. It is also important to remember that the way this heatsink is oriented means that the airflow it creates will work directly against the natural airflow characteristics of most enclosures on the market.

Acoustical Characteristics

When at idle, everything quiet in the realm of the Sapphire HD3870 Toxic but when under load, the second the core hits 66°C, all hell breaks loose. Fan speed immediately increases to an ear-splittingly loud 50% which quickly downs out any case and CPU fans you might be using. Luckily for our sanity, the temperatures hovered at that magical 65-66°C mark since anything more and I couldn’t guarantee you that my sanity would have been left in check. It simply beggars comprehension that this fan spinning at a “mere” 50% of its maximum rotational speed could cause such an uproar.

Basically, using this card for HTCP use is a no-go at its default speed since its fan will spin up to 50% and thus insane decibel levels after about 15 minutes of HD decoding. It is true that you can use a program like Rivatuner to modify the fan speed profiles but let’s be honest; not many customers will go through this process. Let us end this section by making one thing clear to you: if you are considering buying this card, as you will see in the next section, Rivatuner is your best friend.