Hello and welcome to Bleepingcomputer.
Do you remember what was repaired when HP repaired it the last time?
The process of re-flowing is performed by placing the video card into an oven after it is pre-heated to 350 Degrees F.
The video card has to be stripped of any plastic parts that might melt. (If possible.)
The card has to be in the open for 10 minutes, then the oven is turned off and the card is left as it is, moving it may cause the liquefied molten solder to spill over causing solder bridges, which is not what you want.
Open the oven door and wait 30 minutes before attempting to touch or move the card.
Put back any plastic parts and re-try the card.
You may have to repeat the process a second time, if the first time fails.
More experienced electronically inclined people can repair solder connections by carefully using a low powered 15 watt grounded soldering pencil and a keen eye and steady hand under magification.
If that fails, the card has a defective component.
Edited by MrBruce1959, 12 July 2010 - 10:25 PM.