Although the graphics chip is usually down-clocked to 240 or 500 MHz, the GDDR5 memory on older cards tends to stay at its top speed. For cards built around an ATI chip, scaling will depend on the model. The cooler’s fans are never idle, either.Īs a rule of thumb, frequencies should drop to 300/600/100 MHz (GPU/shader/memory) in 2D mode on Nvidia cards. The other side-effect of the GPU being stuck at max speed is that it constantly produces the same amount of heat, whether you’re browsing the Web or playing a graphically-demanding 3D game. The only winning party here is your power company. While this does boost 3D performance under load, locking the graphics chip in to a higher overclocked frequency means the board doesn't scale down when idle. They overclock the GPU by five percent and sell the card as an OC Edition. In some cases, card makers don’t do their homework. Ideally, both should support overclocking and clock scaling (lowering the clock speeds for the GPU and memory when the card is in 2D mode) where possible. Two more points to consider are the card’s BIOS and its graphics drivers. And while the fan will try to cope with the additional heat by blowing more air onto the cooler, it can only do so much with the surface area it has at its disposal. Usually, stock coolers only provide a little headroom. Once this point is reached, the card is running at the highest clock speed the cooler will enable. If you go and increase your GPU's core frequency, resulting in higher heat output, the fan will become progressively louder, spinning up until it reaches its maximum speed in an effort to keep the graphics chip from overheating. This is a very important point, since a reference cooler is designed to keep the GPU at a temperature of about 80 to 90 degrees Celsius at stock speeds while (hopefully) producing only moderate noise. Along the same lines, a bigger heat sink is also beneficial, as the thermal load can be dissipated over a larger area. Heatpipes are good, and more heatpipes tend to be better. While the reference designs that grace the first cards to hit the market do their jobs well enough, after-market solutions tend to yield better results, as do models carrying a manufacturer’s own design.
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