ATX Specification (Version 2.2) писал(-а):
Voltage Rail       Tolerance

+5VDC              ± 5 %
-5VDC (if used)    ± 10 %
+12VDC             ± 5 %
-12VDC             ± 10 %
+3.3VDC            ± 5 %
+5VSB              ± 5 %