Apple issued the anticipated firmware update for their 27-inch iMacs

In this knowledgebase document on the update, Apple suggests if you continue to experience display flickering issues after the firmware update has been applied, you should check to ensure you have applied the previously released "27-inch iMac Graphics Firmware Update 1.0," which updated the graphics cards on the new systems.
Since these updates and the problems they address have to do with firmware, you might try resetting the system's PRAM and SMC after you have applied the update. Doing this should reset firmware settings and configurations to default values, and clear any potential contributions to the problem by faulty settings.
Along with the recent update to iTunes that Apple released, the company also issued the anticipated firmware update for their 27-inch iMacs which is an update for the display hardware itself, and is supposed to help address video problems that have plagued the new machines. These have included blank displays, yellow-tinted LCD colors, and display flickering, of which the latter is addressed by this update.
Initial reports on the update appear to be mixed. So far, people who have not had any flickering problems with their iMacs have not noticed any difference upon applying the update. However, a few members on the Apple discussion boards have commented that applying the update has made the problem worse. Despite these instances, for others the update has worked as expected.

See more laptop accessories information on feevoo.com, or just visit here: Dell 06G356 AC Adapter(Input: AC100-240V (worldwide use)
Dell PA-1900-02D AC Adapter(Input: AC100-240V (worldwide use) Output: DC19.5V 4.62A Power: 90W)
Sony VGP-AC16V13 AC Adapter(Input: AC100-240V - 50/60HZ (Worldwide Compatible) Output: DC16V 4A Power: 64W )
Dell PA-1650-05D AC Adapter(Input: AC100-240V (worldwide use)
Output: DC19.5V 3.34A)
Dell PA-12 AC Adapter (Input: AC100-240V (worldwide use)
Output: DC19.5V 3.34A )
HP 402018-001 AC Adapter(Input: AC100-240V 50-60Hz (Worldwide Compatible) Output: 18.5V 3.5A Power: 65W)
hp 381090 001(hp 381090 001 )
hp 417220 001(hp 417220 001)

Dell Inspiron 1525 Battery(Type: Li-ion, 9 cells Voltage: 11.1V Capacity: 6600MAH )

Compaq Presario CQ40 Battery(Voltage: 10.8V Capacity: 8800MAH )

Dell Inspiron 1526 Battery(Type: Li-ion, 9 cells Voltage: 11.1V Capacity: 6600MAH )