Sorry for the English. Wrote a translator.
The fan on the Radeon HD 4870 may be turned off, then turn on. Sometimes as disconnected and may not work for as long as the computer itself from the heat turns off. Fan clean and lubricate. And what happen on the screen artifacts shake. Often will freeze and all. Attributed to the diagnosis. They said that the chip is overheated. Nothing could be done.
Instead HD 4870 decided to put the new Radeon HD 7750. So computer freezes even in BIOS mode.
http://flickr.com/gp/98512652 @ N04/p2o97Y
The buttons on the keyboard do not respond. Also attributed to the diagnosis. On 2 sistemnike refuses to work. The Master said non-working card. I tested it with your friend. So she plows. Delivered, installed the driver. To test played in WOT. He stands motherboard Asrock H55DE3.
Here is my Intel DP35DP.