A while back I posted a thread showing how you could use a PC case, a PC PSU, and a Mac PCIe external controller to build an extremely reliable, high-capacity, and extremely fast drive setup. Many external solutions use "power bricks" / "Wall worts" which are of dubious quality. Most are overpriced. Some use inferior and overpriced USBIII. This thread is about how to make your own. Though this is mainly directed to people with PCIe slots, nMP users may eventually be able to use this information to escape the insane premiums they're paying for external storage (as TB2-> SATA controllers come available). Controller eSATA The first question you must ask is what kind of controller to buy. This question requires you to answer more questions: How many drives do you want, how fast do you want them, and how much money do you have. From what I can tell, most eSATA III cards for Mac use the same or similar controllers by a company called Marvell. This includes the Highpoint RocketRAID 644L and 642L as well as the Syba cards (search the forums for more information on those). These cards seem to work extremely well. They sleep, most of them support TRIM (see my review of the 644L, which is an exception), and they generally function without issue. The problem with these cards (if you even want to call it a problem) is that some don't support port multiplication which is often desirable and they are all limited on throughput to 1GBps -- that's PCIe 2.0 1x. You can put them in the 4x port in your Mac Pro but they will never go faster than 1GBps. On my 644L, I was only able to get around 700MBps. There are also SATA 2 options, and for platter drives that seems to be fine. Port multiplication is a feature supported on a lot of eSATA cards including the RocketRAID series from highpoint. Basically you have a circuit board which shares one SATA channel into 4 or 5. I have been using two Addonics controllers for years and they work great! Here is the latest model which is even SATA III! eSATA price tag: Port multipliers are around $75, 4 port eSATA cards are < $100. Therefore, the totals are as follows: $100 - 4 drives (no PM) $175 - 8 drives (1 PM) $250 - 12 drives (2 PM) $325 - 16 drives (3 PM) $400 - 20 drives (4 PM) MiniSAS Another great option is MiniSAS. MiniSAS is basically four SATA III ports in each port. You use a simple adapter to split the port with no performance loss. It's controllers like these you see demonstrated with SATA SSDs getting 500MBps per drive (4 drives in RAID 0 getting 2GBps!)! Does MiniSAS support port multiplication? Why yes, yes it does. Usually they call them "expanders" and there are a lot of them out there that do 1 -> 4, allowing you to plug in 16 drives to every MiniSAS port (instead of 4)!! They are pricey, however, but keep in mind this is 33% more bandwidth than three SATA III 5-port multipliers, has 1 extra port, and costs 40% more. I'm going to use HighPoint cards as they've been reviewed at several Mac sites and generally receive good marks. This card by Highpoint is the RocketRAID 2722. It supports Two MiniSAS connections capable of up to 8 drives for a total of 4GBps (realistically probably around 2600MBpS with PCIe overhead). I found it here for $279. This card by Highpoint is the RocketRAID 2744, which requires a PCIe 16x slot and supports FOUR miniSAS connections capable of up to 16 drives for a total of 8GBps (realistically probably around 5,200MBps with PCIe overhead). I found it for $427. MiniSAS price tag: $280 - 8 drives @4GBps - RR2722 $427 - 16 drives @8GBps - RR2744 $594 - 20 drives @4GBps - RR2722 + SAS Expander $741 - 28 drives @8GBps - RR2744 + SAS Expander $908 - 32 drives @4GBps - RR2722 + 2x SAS Expander $1055 - 40 drives @8GBps - RR2744 + 2x SAS Expander And so on. You can see that it's possible to have an insane amount of drives and bandwidth with MiniSAS. Backplane What I'd recommend looking at first is a backplane, especially if you're using 3.5" drives. 2.5" drives can be adapted to work in 3.5" bays for about $15. While you don't need one, they make it easier to access the drives, give you indicator lights, and often include a fan to keep your drives cool. It's kind of like a miniature PC case inside your big PC case dedicated to taking care of your drives. There are two models that have great price/performance: a 4 in 3 and a 5 in 3 First let's show a cheap one so you can get an idea of what we're talking about. Here's one that is less than $25 by coolermaster, it holds 4 hard drives, has an included 120mm fan, and is SILENT (I own one): Here is an example of these in use: There it is, a silent 12 drive enclosure for $75 + case + PSU (get to those later). Here is another one by Icy Dock which is about $130, holds 4 drives, requires no screws, is hot-swappable, and has an 80mm fan. This is probably what I'd recommend most. And then here come the 5 in 3 models. You shouldn't pay more than $150 for these. They hold 5 drives, usually have a 92mm fan, and work fine. The disadvantage is you have to bend down the fins on the case you use to throw these in. Also, unlike the 4 in 3 models, you have to screw each drive into a carrier to use it. Here is an example of this kind of setup: Personally I use two 5 in 3 because I needed the extra drives, but if you can make do with the 4 in 3, your life will be easier Case The easier (or harder) choice is coming up with a case to throw your drives into. When you see how cheap these are, you'll never buy a pre-made enclosure again. Watch out though, some of them look pretty silly... But they work! If you're using a backplane that fits into three 5.25" bays, you're going to want a case with bays in multiples of three. Here is a 12 bay model for $155. If you're really trying to save money, just look for any old PC case that has 3.5" (or 2.5") bays. You can pay as little as $25 for one (that one holds 5 hard drives). Power Supply Power supplies are better than ever in the PC world. Always make sure you have an UPS. Some good brands: Thermaltake, Antec, Rosewill (yes, Rosewill), Corsair. The 80 Plus Silver, Gold, Platinum monikers refer to efficiency only. For reliability, I'd recommend jumping onto NewEgg.com and looking at the reviews--some have over 1000 reviews! You want at least a 450W PSU, and I'd recommend a single 12V rail so you don't have to be clever with your wiring. I found a 80 Plus Platinum 550Watt Rosewill PSU for $80! Cables If you pay more than $5 a cable, you paid too much (accepting the MiniSAS to SATA cables) Bottom Line Here are some various examples of setups. I'll use my Rosewill PSU I mentioned above though you can get cheaper than this! I included the bandwidth/drive but note that these setups are using shared bandwidth--therefore the max MBps listed here are under a scenario where you're running all the drives in a RAID-0 or are otherwise using all the drives at once. Each individual drive (especially on the MiniSAS cards) should be able to get up to their full SATA III potential (500-750MBps) as long as other drives aren't using the bandwidth on the channel. $210 ($53/drive) - 4 drives @ 1GBps (250MBps/drive) - $100 eSATA + $25 PC case + $80 PSU + $1x4 SATA cables - (Add $120 for one 4 in 3 screw-less back plane) $401 ($40/drive) - 10 drives @ 1GBps (100MBps/drive) - $100 eSata + $75x2 Port Mutlipliers + $65 PC case + $80 PSU + $1x6 SATA cables - (add $300 for two 5 in 3 back planes) $480 ($59/drive) - 8 drives @4GBps (500MBps/drive) - $280 RR2722 + $65 PC case + $80 PSU + $15x2miniSAS/sata cables + $5x2 MiniSAS cables - (add $240 for two 4 in 3 screwless back planes) $1227 ($77/drive) - 16 drives @8GBps (500MBps/drive) - $427 RR2744 + $160 PC case + $80 PSU + $15x4miniSAS/sata cables + $5x4 MiniSAS cables + $120x4 four-in-three screwless backplanes $1,264 ($64/drive) - 20 drives @1GBps (50MBps/Drive) - $100 eSATA + $160 PC case + $80 PSU + $75x4 port multipliers + $1x24 SATA cables + $150x4 five-in-three backplanes $1,510 ($76/drive) - 20 drives@4GBps (200MBps/drive) - $280 RR2722 + $320x1 SAS Expander + $160 PC Case + $80 PSU + $15x4 MiniSAS->SATA cables + $5x2 MiniSAS Cables + $150x4 five-in-three backplanes And finally, just to demonstrate the versatility of this kind of setup, here's what it would take to hook 64 drives up using this method, with more bandwidth than all the TB2 ports on the nMP combined. This combination is basically four separate enclosures hooked to a single controller. In the old Mac Pro, you could throw this into Slot2, but if you didn't mind having a 4xPCIe video card, you could potentially have two of these setup for a total of 128 drives at 16GBps!! $4,847 ($76/drive) - 64 drives@8GBps (125MBps/drive) - $427 RR2744 + $320x4 SAS Expander + $160x4 PC Case + $80x4 PSU + $15x16 MiniSAS->SATA Cables + $5x4 MiniSAS Cables + $120x16 four-in-three screwless backplanes This requires very little technical knowledge, will give you more reliable hardware (power bricks? are you freaking kidding me?), and will save you a bunch of money. I should note that what inspired me to re-write this post was seeing another thread talking about 12 bay dual port Thunderbolt 2 enclosures retailing for $2200 ($183/drive, 334MBps/drive). As you can see, you can get a product for almost $1000 less which has 4 times the bandwidth as TB2, holds 33% more drives, and is upgradable and adaptable. Since the new Mac Pro only has three TB2 controllers, an 8GBps MiniSAS controller will actually have 33% more bandwidth for drives than all six TB2 ports combined. This really indicates the need for cheaper and al a cart TB2 to SATA options, which are insanely overpriced at the moment.