I have around 10 6 gpu rigs running this setup with no problems only had one die on me.
The finsky solution along with all the cables and the mother board adapaters could ealy cost 2-3 times the cost of buying normal PSU's
This math is not a good example and no way it's even more expensive never mind being 2-3 times.
4 of those Rosewill 1KW even at your Super Sales price is $480. You really can't compare a super blow out once in a while sale but I'll use it anyway as it's an extreme example.
Finksy 4KW bundle is much less than this. His Triple A package is $255 and includes everything you need including 30 cables, power cables, fan mount, fans, the complete deal. Now if Finksy can get the Pico with Custom cables at $25-30 x 4 that's up to a Max of $120. So your total price is $375. Way cheaper than your extreme example.
***** The MORE ACCURATE Comparison ***********
Most people are not powering just 470s or as efficient with undervolting as you Marvell. You simply can't push 7 x 480 on a 1KW nor would you be able to do 6 x Furies, 5 x 390, Vegas, yadda yadda. So a more accurate comparison is against 4 x EVGA 1300 which normally sell for $200-235 after tax. Let's not count Black Friday SUPER Sales or 1 offs, let's compare average selling price, the what does it cost if I need NOW... . We're then talking easily over $1K of PSU and they're not future proof if your rig requires more than 1000-1300w which means now have double the cost for each rig with 2 PSU and an even uglier Bird's nest in the rear blocking flow.
Don't forget even if you don't choose the 4KW bundle, and chose YSLUNG HP 1200W server PSU for separate individual controls, it's still much cheaper and you're getting Enterprise server PSU compare to consumer grade ATX. Of course the ATX comes with better resell value and warranty which is a plus but the server PSU is so cheap, you can buy plenty of extra spares and still have money left over for Dinner and a movie with the entire family. Also you don't have to leave your rig down for a few weeks waiting for that dead Rosewill RMA. Spare server PSUs are like $18-45 depending on whether you're choosing HP or IBM so you can do your own immediate Warranty maintenance. Don't get me wrong, there's plenty of places where ATX make sense like my Server case rigs but that may change in the future as well.
This is why I'm pushing hard on Finksy, Hawkfish and YSLUNG to get us GOOD PICOs for reasonable price of below $30. If it's at $50 and above, the value proposition drops a lot. However, wait until you see the CRAZY designs I'm going to be coming up with that is only made POSSIBLE by HAWKFISH007 PCI risers and PICOs. IT will be BAD ass and something very unique making even pricey Picos worth it. You also lose the Birds nest of ATX PSU and cables in the rear blocking flow..... ...............Stay Tune...............
Three Different Designs
1) Server PSU w Picos for Server Case
2) A Standing Tower Rig
3) The most compact RISER powered stacking Rig
A Psu is 40 bucks?
You can have multiple spares, all the other gear is reusable.
You can easily have backup server psu and swap them out with VERY little work/effort/down time.
With a pc psu even if you have a warranty you are looking at 30 days return, or a pricey replacement/more work to rewire a psu. so longer down time
part of the cost is the cables and breakout board