From what I know about heat treat ageing of metals something similar may be happening. Because he is pushing his system through above average temperature cycles, this causes microcrystalline changes in the solder. Ageing at even a temperature below reflow/melt temperatures can help restructure the grain.
If he didn't run his system at such a high temp and then eventually turn it off to cool so much then he might not have the problem to begin with. As a side note, personal experience building pcs for many years has shown me that pcs that sleep/get powered off don't last as long as ones that stay powered on 24/7.
From what I know about heat treat ageing of metals something similar may be happening. Because he is pushing his system through above average temperature cycles, this causes microcrystalline changes in the solder. Ageing at even a temperature below reflow/melt temperatures can help restructure the grain.
If he didn't run his system at such a high temp and then eventually turn it off to cool so much then he might not have the problem to begin with. As a side note, personal experience building pcs for many years has shown me that pcs that sleep/get powered off don't last as long as ones that stay powered on 24/7.