How Can I Assess The Quality Of a Graphics Card?

When finding a new graphics card, what figures or features do I look at when comparing two graphics cards? Dual cores? Clock speed? etc

With graphics cards, there are so many factors that determine performance, it really is near impossible to do it from a specification list.

If you want to see raw performance difference, I highly advise you use the big list at Video Card Benchmark

Tom's Hardware has a regularly updated graphics card hierarchy chart, this is very useful to compare between 2 chips when you're unsure of the relative performance.

For Linux you'll still need to find out the driver support separately, few years back nVidia used to have far better results so people would avoid ATI cards, but more recently AMD seems to have better Linux driver support - don't know if that has changed again, but esp. for latest chipsets you need to check that they have stable Linux driver support.

• Clock/RAM Speed
• Graphics Memory Amount and Bandwidth
• Chipset
• Processing Cores
• Display Connectors
• DirectX Support (Preferably DirectX 11)
• Availability of SLI or CrossFireX
• Slot on which the card sits (PCI-E is faster than PCI)
• Support of DirectX (9, 10, 11)
• Performance for HD videos (Not a direct consequence but still worth considering)

The memory speeds play a key role in the graphics card abilities and are far superior.

 Type         Clock Speed(MHz)        Bandwidth (GB/s)     
 DDR            166 - 950           1.2 - 30.4     
 DDR2           533 - 1000          8.5 - 16     
 GDDR3          700 - 2400          5.6 - 156.6     
 GDDR4          2000 - 3600         128 - 200    
 GDDR5          900 - 5600          130 - 230