I am trying to finalise my PSU choice, I have carried out a PSU calculation using the Coolermaster online calculator, it suggests I need a minimum 700W power supply. See result below: https://dl.dropbox.com/u/47274064/IMG_1307.PNG
PLEAE NOTE: This is based on a Xeon processor as I may be getting this instead of an i5, for better performance on my analysis work. Also this is based on MAX set up of the system which I think I will end up with over the next few years.
To try and keep build costs low I have thought about getting either
I am not too worried if it is modular or not, my case has a big compartment to hide excess cables and my case does not have a window. I want to go for which ever power supply is the better one.
I have two questions
1) For the money am I getting the “best bang for my buck”? Or could I do better?
2) Which of the two OCZ PSU’s above would be the better choice, not taking into account the modularity of the modxstream?
I would really appreciate you input, please thank you.
I seriously doubt that the MXSP700W would be able to support a build with two 7970s.
This is because it only has 552W available on it's +12V rails; the majority of the 694W number given by CM's calc is going to need to be deliverable on the +12V rail.
Secondly, it doesn't have enough PCIe connectors (only two, you need four).
Thirdly, the +12V rail arrangement is pretty crap on that unit, especially if you want to try to use molex to PCIe converters. They are all on +12V2, which is only rated to 25A, which is 300W.
So the OCZ ZS Series 750W is definitely the better choice because it has a higher capacity +12V rail (54A / 648W), it has the necessary connectors, it uses a more modern and efficient design. As you can see your potential build would still overload the ZS Series 750W unit, so I think you need to spend more to get a high quality 750W (with most of it's output capacity on the +12V rail).
These are two of the cheapest, high quality, 'proper' 750W PSUs that I know of:
Antec Truepower New TP-750 (£70 @ Scan) http://skinflint.co.uk/407704
I do think that 694W is an overestimation for the power consumption of your system, but 750W is definitely a good size of power supply for a system with two 7970s.
The original 7970 has a maximum TDP of 250W.