Video card

( from wikipedia )








Graphics processing unit (GPU)
A GPU is a dedicated graphics microprocessor optimized for floating point calculations which are fundamental to 3D graphics rendering. The main attributes of the GPU are the core clock rate, which typically ranges from 250 MHz to 1200 MHz in modern cards, and the number of pipelines (vertex and fragment shaders), which translate a 3D image characterized by vertices and lines into a 2D image formed by pixels.

Video memory
If the video card is integrated in the motherboard, it will use the computer RAM memory (lower throughput). If it is not integrated, the video card will have its own video memory which is called Video RAM or VRAM. The VRAM capacity of most modern video cards range from 128 to 1024 MB. Before 2003, the VRAM was typically based on DDR technology. During and after that year, manufacturers moved towards the vastly superior DDR2, GDDR3 and GDDR4. The memory clock rate in modern cards are generally between 400 MHz and 1.6 GHz. A very important element of the video memory is the Z-buffer, which manages the depth coordinates in 3D graphics.

Video BIOS
The video BIOS or firmware chip is a chip that contains the basic program that governs the video card's operations and provides the instructions that allow the computer and software to interface with the card. It contains information on the memory timing, operating speeds and voltages of the processor and ram and other information. It is possible to re-flash a BIOS (enable factory-locked settings for higher performance) although this is typically only done by video card overclockers, and has the potential to irreversibly damage the card.

RAMDAC
Random Access Memory Digital-to-Analog Converter. RAMDAC takes responsibility for turning the digital signals produced by the computer processor into an analog signal which can be understood by the computer display. Depending on the number of bits used and the RAMDAC data transfer rate, the converter will be able to support different computer display refresh rates. With CRT displays, it is best to work over 75 Hz and never under 60 Hz, in order to minimise flicker. (With LCD displays, flicker is not a problem.) Due to the growing popularity of digital computer displays and the migration of some of its functions to the motherboard, the RAMDAC is slowly disappearing. All current LCD and plasma displays and TVs work in the digital domain and do not require a RAMDAC. There are few remaining legacy LCD and plasma displays which feature analog inputs (VGA, component, SCART etc.) only; these do require a RAMDAC but they reconvert the analog signal back to digital before they can display it, with the unavoidable loss of quality stemming from this digital-to-analog-to-digital conversion.

Cooling devices











Heat sink with fan attached.
Due to video card work charge, high temperatures are reached, which can cause a breakdown. Cooling devices are incorporated to avoid excessive heat. There are two types of cooling devices, and both can be used at the same time:

• Heat sink: generally referred to as a passive cooling device, it has no moving parts and, therefore, is soundless and very reliable; it absorbs and dissipates heat from the GPU using thermal contact (by either direct or radiant contact with a cooling medium such as air). Its effectiveness depends on its size and other characteristics including shape and material (generally copper or aluminium).
• Computer fan: usually known as an active cooling device, it has moving parts to push hot air away from the video card and as such will generate a small amount of noise. It is more effective than a heat sink at cooling, but due to the moving parts is far less reliable than a passive heat-sink.
• Water Block (See: liquid cooling): uses liquid and heat sinks to cool the GPU. This method is used less often but is much more favorable to both other options as it is more effective than a fan and soundless just like a passive cooling device.