This definition blows for the reasons below (mainly the other definitions deal with facts and this one has too many opinions that can vary)
Some Haswell compatible, some not (maybe unconfirmed). Still safe to use and stable, just lower quality components. Some capacitors maybe Japanese, but can include the Taiwanese capacitors. Not really ideal in serious overclocking or super-high load situations, such as a Bitcoin mining rig or a high end gaming system.
1. what is serious over clocking? If my system draws 325w even when OC, it won't work on a tier 3 PSU?
2. what is a high load situation? 50, 60, 70%? I have this dude telling me a need a 750w PSU to run a single GTX770 so should I then go one tier down for a 750w since that is all I can afford!
The definition should simply state
Some Haswell compatible, some not (maybe unconfirmed), still safe to use. Some capacitors maybe Japanese, but can include the Taiwanese capacitors. Not really ideal in overclocking, Bitcoin mining rig, or a gaming system that will constantly push power requirements towards the top end of the PSU’s ability.
Serious overclocking as in -
SLi / Crossfire overclocking, high end CPU overclocking w/ extreme high end hardware + memory overclocking.
A decent overclock is fine for tier 3 units, but I would only suggest overclocking the CPU.