I'm putting together a newish rig from old and new parts and the PSU needed is going to be a beast.
The hardware list will be something like this:
Asus Z9PE-D8
2x Intel Xeon E5-2620
32Gb of RAM
2x AMD R9 290 in CF (maybe more in the future..)
Asus Xonar DX
Some wireless network PCI-E card
6x mechanical HDD
2x SSD
A bunch of fans...
I've read up on the motherboard and it's picky on the needed power and requires 1x24pin, 2x8pin and a molex for additional power delivery just to the motherboard. Then there's the graphics cards and the sound card also require some additional power.
I've found a second hand Enermax Platimax 1500W (for about 300$) that seems to be a nice fit but what other options are there and is that a good PSU (always been a Silverstone user my self)?
Be very careful with the 290s I've seen mine use almost 400w each at absolute max load. For two way, you're looking at 1000w minimum. For 3 way, 1400w minimum. I have researched this topic and the enermax is an excellent choice. I own the lepa maxplatinum (almost same model) and its powering 3 way 290s. Other options I have heard about are the corsair ax1500i and the upcoming EVGA nex1500w refresh (supposedly its 1600w) but I'm unsure about the the release date.
I see you're using dual Xeons and dual 290s, so I assume budget is virtually infinite. Therefore, why not get 780 Ti's if you're gaming or a Titan/Quadro if you're rendering/computing? If you need Radeon parts specifically, consider 290X's instead because why not?
Are you going to watercool this system too? If you include multiple GPUs in the future, water-cooling becomes a viable option to maintain decent temperatures rather than relying on air coolers to dissipate the heat. If so, your rig will consume even more power than it already would be, just something to consider. And at this budget, unless you need extreme stability and reliability, water cooling would be very justifiable and in my opinion recommendable.
I would say you need around 1300 W give or take (1200 W at the bare minimum) to cater for everything (dual CPUs, multiple GPUs, half a dozen HDDs, fans, pump(s) maybe, etc). And definitely go at least gold efficiency if not platinum. Any reputable brand that sells high wattage platinum efficiency power supplies should be perfect. Some that come to mind are the Antec HCP-1300 Platinum and the Corsair AX1200i. Or, I would consider going dual power supplies if your case supports it.
Both Gaming, folding and a bit of playing with VM's.
Windows 8.1 makes that possible, the lower core clocks would have been an issue before but since I play older games or really new games with excellent multi-thread support it will probably work just fine.
How new is the Platimax? They are indeed very nice units. As for $300, I think that is a little steep. Since the mining boom as subsided a fair bit (well it has here in Oz anyway) you should be able to pick up other decent uber-high wattage units as a good price.
If you purchase new, some ones to look out for that will be around the $300 mark:
I'm currently running an Silverstone Strider Gold ST1000G but that won't be enough by far for this and the Enermax Platimax 1500W I've found second hand for 300$ seems like the best bang for the buck that can handle the motherboard....
Why not grab another silverstone Strider Gold? I run a 1200 but if you need extra power there are ways including little cards that power on and off one PSU from the state that the other PSU is in. Otherwise you wont really find what you are looking for without going server class PSU's