if a motherboard runs 24/7 non-stop compare to a motherboard that has 2-4hrs rest everyday. which one will last longer?
For electronic goods the harshest thing is powering up. I have an Asus P5K-E motherboard that has run 24/7 about 6+ years now, and my current system has run 24/7 about 2 years now.
All my rigs run 24\7 with overclock, never had any die on me yet or degrade for that matter. I've had to retire a few simply because they outlived their usefulness. Oldest running rig was seven years but I put it down when XP support ended.
Impossible to say really. Depends on quality control that day. Generally speaking though it's actually better to leave it on permanently.
I support several dozen servers at work. Mobo failure is almost never the problem that kills a server. Its usually the HDDs that go first, followed by PSs.
How about sleep state ? Better to still let it run 24/7 still than letting it go to sleep ? Or its still the same thing as powering it up from a shutdown ?