Pantip Plaza Electronics Mall is Bangkok’s mecca for electrics. Found in the central Pratunam area this is where locals go for their IT needs. On the ground floor stores sell counterfeit software and DVDs. The 2nd floor mezzanine is best for IT repairs. The higher floors tend to be a mix of hardware and electronics. If forced to wait the 3rd floor has a Thai food court and on the ground floor Western junk food.
For hardware repairs and upgrades Leng IT on the 2nd floor is a good start (we find them cheapest and most trustworthy). With prices like nowhere else in Bangkok Pantip Plaza Electronics Mall is every techie’s wet dream. For further information on Pantip Plaza check their website.