OCZ ProXStream 1000 W Power Supply Review
Power Distribution
Contents
In Figure 15, you can see the label from this power supply containing all its power specs.
Figure 15: Power supply label.
The +3.3 V output is labeled at 28 A or 92.4 W and the +5 V output is labeled at 30 A or 150 W. Funny enough the label says that the maximum combined power for these two outputs is of 150 W – which is strange, as on this power supply these two outputs don’t share any components. Maybe the unit was labeled this way just to fulfill ATX standard.
As you can see, this power supply has four +12 V rails, each one labeled at 20 A or 240 W. This would give a total +12 V power of 960 W but the label says that the maximum combined +12 V current is of 70 A, which equals to 840 W.
Adding this 840 W to the 150 W combined power of the +3.3 V and + 5 V we have 990 W, but the label says that the maximum combined power for all these outputs is of 976.5 W. Adding this to the +5VSB maximum power (17.5 W) and to the -12 V maximum power (6 W) we have exactly 1,000 W.
As we mentioned OCZ didn’t post at what temperature they labeled their power supply but don’t worry, we will test this during our load tests.
As for power distribution, as mentioned this unit has four +12 V virtual rails, +12V1 (yellow wire with black stripe), +12V2 (solid yellow line), +12V3 (yellow wire with blue stripe) and +12V4 (yellow wire with green stripe). On OCZ ProXStream 1000 W the power distribution is the following:
- +12V1: EPS12V connector
- +12V2: All peripheral cables, main 20/24-pin motherboard connector, ATX12V connector
- +12V3: PCIE1 and PCIE2 connectors
- +12V4: PCIE3 and PCIE4 connectors
We think that there are two problems here. The EPS12V is the only connector on +12V1. So if your motherboard has an EPS12V connector, use it instead of the ATX12V connector. This will provide a better power distribution. For the regular user with a motherboard with just one CPU a better power distribution would be with the ATX12V connector on +12V1 together with the EPS12V connector, but probably OCZ did this way thinking on users with two CPU systems.
The second problem is with the naming of the PCIE connectors. If you have only two video cards on your system using SLI or Crossfire, you will probably connect PCIE1 plug to the first card and the PCIE2 plug to the second card. After all, that is the way it is labeled. You will get a better power distribution if you connect PCIE1 cable to the first card and PCIE3 cable (and not PCIE2) to the second card. We think that OCZ/FSP should have labeled these connectors differently (i.e., labeling PCIE2 as “PCIE3” and PCIE3 as “PCIE2”).
Why is this so important? The maximum labeled current for each rail is the level when the OCP (Over Current Protection) kicks in (actually it enters in action at a level a little bit above of what is labeled). If you have two very high-end video cards connected to the same rail and if they together consume more than 240 W, the overcurrent protection will shut down your power supply, even with your computer theoretically running inside its specs. Putting each card on a separated rail prevents this from happening, as you will now have a limit of 240 W for each card (480 W total).