A few data points pertinent to those PSUs:
OCZ ModXStream 700W:- Very unimpressive - by today's standards - 550W at 12V rails due to the unit being a...
- ...dated design. (it's a 2008 PSU, folks)
-
Cheap^WHigh-value components made the unit struggle at higher loads. (
HardOCP)
- Very few PCIe connectors (one 6 pin, one 8 pin) necessitate the use of adapters.
OCZ Fatal1ty 750W:- Quad rail design means you need to pay close attention to how you wire things.
Moreover, the rail distribution is wacky:
12V1 (solid yellow wires): Main motherboard cable.
12V2 (yellow/red wires): Half of the ATX12V/EPS12V connector (ummm... wtf?).
12V3 (yellow/green wires): Half of the ATX12V/EPS12V connector, half of the modular connectors (two for video cards and two for SATA/peripheral).
12V4 (yellow/black wires): EPS12V connector, half of the modular connectors (two for video cards and two for SATA/peripheral). (
HardwareSecrets)
- Two hardwired CPU connectors might necessitate the use of an ATX12V->PCIe adapter.
- The unit burnt down under an overload condition instead of safely shutting down. (
HardwareSecrets)
As long as the limitations of both units are understood, the rebated price tags make this opportunity a no-brainer.
