Tier 1 Brands - The Most Powerful And Stable Components On The Market .
Tier 2 Brands - Top Quality components With Top Notch Stability - For Those With Price/Availability Issues With Tier 1
Tier 2b - Tier 2 units which have either lower longevity or slightly lower quality output. Still well within spec, and are good units.
Tier 3 Brands - Power supplies fully able to meet ATX specs, although closer to the edges of the limits than higher tier units. Still solid units.
Tier 4 - Not Recommend for stressful situations. May not be able to put out full rated power above room temperature, and may slightly fail to meet ATX specs.
Tier 5 - Other than the units listed above for any of these brands, NOT RECOMMENDED . Replace ASAP if you have one.