eutectic tin/lead solder melts at 183ºC so the 190ºC you used is lill higher, remelts the joints and bonds are reformed. Though I have to say, 10min heat (+cooldown at room temp) is a little long time for a reflow cycle. Might have been better to crank it up to 220ºC for shorter period. lol
pretty neat anyways
edit, the hardforum thread shows pics of the board with RoHS compliant sticker, 'normal' leadfree solder melts at 218ºC so it should't have melted the joints only at 196ºC (385f). Maybe the solder used is some more uncommon type or the temperature control of the oven is a bit off...
so you are saying that solder joints can just go like any time with heavy use??
No, the 190 C that it was in at is well above the safe operating range, at that are well past being able to make tea on your computer, you would have destroyed any heat pipes or liquid cooling used to cool the card.
@ thaoval: As I gather, it is more like metal fatigue: as the card heats and cools it expands and contracts but not evenly, causing localised stress on certain joints which ulitmately fail and become non-conductive.
Sustained high temperatures or constaint use do not cause this because there is no heating/cooling cycle.
When metals heat and cool they change size, each time they go through one of those cycles they get weaker until the joint eventually cracks, the thinner joints will crack first, the oven gets the solder back up to the temperature where it melts so it reforms the connections properly. its like taking a soldering iron to each joint to fix it just a bit faster
and different materials used in a modern card have different coefficients of thermal expansion, the board itself, solders used, the component casings and substrates and the silicon chips themselves. all these contribute to stresses that affect the solder joints and eventually breaks them...
ok, i get it... i thought about that when the cooler was aluminium but the little square block cooling the chip was copper... different metals... different expansions=stresses form... but it happens for everything