Reddit mentions of ICY DOCK 2.5" to 3.5" SAS/SATA HDD & SSD Converter/Mount/Kit/Adapter - EZConvert MB882SP-1S-2B

https://www.amazon.com/EZConvert-MB882SP-1S-2B-Weight-Converter-Mounting/dp/B002Z2QDNE

Use 100's of these at my work. Easiest and best option in my opinion.

This is what I ultimately bought. So far it's working great.

http://www.amazon.com/gp/product/B002Z2QDNE?psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00

I recently put one of these adapters in my 2950 to house my 120GB SSD. Works well.

It's cheap construction, but since I won't be swapping it out frequently, I think it will be fine. Apparently they sell a nicer version (i.e., metal) for like 2x the price.

http://www.amazon.com/gp/product/B002Z2QDNE/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1

They don't come in the 3.5" size, so you need to buy an adapter if you want to install them in the Mac Pro tower. I bought the Icy Dock adapter, and it worked perfectly.

The performance change is absolutely greater than anything else you can do. Boot times are on the order of 5-10 seconds—under 30s to logged in and ready. Software upgrades, compiling, opening and closing big files are practically instantaneous. Adobe PhotoShop CS 5.5 starts in 3-4 seconds. An SSD can often outperform the SATA interface, while a HDD can't even saturate it when used optimally.

You need to install Trim Enabler, which is (legally) free for what matters. Don't listen to others who say the drive(s) have "garbage collection"—it's not the same thing, and only enabling TRIM will guarantee preserving the long-term performance of the SSD. Once you install TE, go into settings and enable "Check for Trim support on boot". This ensures TRIM doesn't get disabled during system updates!

As far as models, if you plan on being a heavy data user, I still recommend the Samsung 840 Pro (must be Pro), the technology is better for power users. On the other hand, I installed a Crucial MX100 model in two laptops recently. They perform great, and are significantly cheaper. I haven't had them as long as the 840.

The process I used for the Mac Pro was to install the OS clean, then point it at my older install. Honestly, I wouldn't do that again. It was slow and more error-prone.

Instead, for the laptops, I used CarbonCopyCloner, and simply clone the OS to a freshly formatted SSD (note: format as Mac Extended (Journaled)). It took a lot less time, and didn't seem to have any negative side effects. Note: the first time you reboot, the OS needs to rebuild all the caches, and Spotlight needs to reindex everything, so it's a bit slower than you'd expect. Let it run for a while or overnight, then you'll see the true performance.

Finally, since I have room for many drives, I keep a spare drive in the computer just for the daily temporary stuff. I actually symlinked my Downloads folder to the spare drive, and I moved all my virtual machines there as well. This reduces wear-and-tear on the SSD, since those are usually temporary files that are used once and then deleted, or big files that I don't really care about. I keep my music and videos there, as well.

Neither, I use ICY DOCK and like devices, you can get Icy Dock for single SSD/HDD to multiple drives. I use it to change my boot drive to transferring data from my PC to laptop and so on. So the 2.5" part is to insert a boot SSD (Window or a Linux distribution OS) and the 3.5" I use to transfer data or back it up to a 6T HDD.

For my desktop I use: https://www.amazon.com/gp/product/B00834SJ8K/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 and https://www.amazon.com/StarTech-com-5-25in-Trayless-Mobile-3-5in/dp/B000KS8S9W/ref=pd_sbs_147_1/145-7509564-3873745?_encoding=UTF8&pd_rd_i=B000KS8S9W&pd_rd_r=eef1512f-6959-4fde-9177-ce62c8768090&pd_rd_w=RY63p&pd_rd_wg=xKSNf&pf_rd_p=5873ae95-9063-4a23-9b7e-eafa738c2269&pf_rd_r=AQ0G50CK9G4ZQWMVKEFQ&psc=1&refRID=AQ0G50CK9G4ZQWMVKEFQ that needs https://www.amazon.com/gp/product/B002Z2QDNE/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1 if I want to use a 2.5" drive to transfer info.

For my laptop https://www.amazon.com/gp/product/B07HY1QLJX/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 so I don't have a DVD any more but any hot swap SSD port now. :-) Or press my keys to select a boot device and boot another OS.

Icy Dock does offer this same technology https://www.icydock.com/goods.php?id=245, just an idea, a flexible idea to me. Win on one NVMe SSD, a Linux distro on an other NVMe SSD, and have as many as you want this way, I do.

A ton of zip ties or velcro straps and two 2.5 to 3.5 converters so you can place it in those 3.5" drive bays. If you don't have enough slack to reroute the cables around the back, get some Silverstone Tek extension cables.

http://www.amazon.com/EZConvert-MB882SP-1S-2B-Weight-Converter-Mounting/dp/B002Z2QDNE

http://www.amazon.com/Silverstone-Extension-Motherboard-Connector-PP07-MBBR/dp/B00HWQUKCS

http://www.amazon.com/Silverstone-Sleeved-Extension-Connector-PP07-EPS8BR/dp/B00H45K58Q

Yes. I've done it. My 2008 Mac Pro is still a monster of a machine! I got an Icy Dock which lets you mount a 2.5 inch drive in the Mac Pro's hard drive bays.

http://www.amazon.com/Icy-Dock-EZConvert-2-5-Inch-Converter/dp/B002Z2QDNE

Once you've got an SSD, just clone (Carbon Copy Cloner) your existing boot drive to the SSD and then swap the drive or put the SSD in one of the three other bays.

As for SSD choice, I'll defer to the other more knowledgeable redditors about that. :)

This was a simple cluster, not really designed for running a lot of VMs. We run 3 AD servers, a File Server, and one server for a special piece of software. That's a total of only 5 Windows 2008 R2 VMs, but you can see that it can handle much more.

>SAN $230: http://www.ebay.com/itm/RACKABLE-2U-SERVER-S5000PSL-2-x-INTEL-QUAD-CORE-L5420-2-5GHz-16GB-1TB-SATA-/121402377113?pt=COMP_EN_Servers&hash=item1c44254399
x2 VM Server $1200: http://www.ebay.com/itm/Dell-PowerEdge-C1100-CS24-TY-1U-2x-XEON-QC-L5520-2-26GHz-4xTRAYS-72GB-DDR3-/261355969100?pt=COMP_EN_Servers&hash=item3cda079a4c
SSD $75: http://www.amazon.com/Crucial-MX100-adapter-Internal-CT128MX100SSD1/dp/B00KFAGD88/
x2 Boot Drives $206: http://www.amazon.com/Seagate-Desktop-3-5-Inch-Internal-ST3000DM001/dp/B005T3GRLY/
x2 Storage Drives $280: http://www.amazon.com/Seagate-Desktop-ST4000DM000-3-5-Inch-Internal/dp/B00B99JU4S/
x3 Batteries $300: http://www.amazon.com/CyberPower-CP1000AVRLCD-Intelligent-1000VA-Mini-Tower/dp/B000QZ3UG0/
Shelf $31: http://www.amazon.com/Odyssey-ARS2-Space-Shelf-Accessory/dp/B0002DV0GI/
Server Rack $281: http://www.amazon.com/Tripp-Lite-SR4POST25-Cabinet-Capacity/dp/B004OB8T72/
Microsoft Server 2008 R2 $695: http://www.amazon.com/Microsoft-Windows-Server-Standard-Packaging/dp/B00H09CF70/
x2 Microsoft Server CALs $298: http://www.amazon.com/Microsoft-Windows-Server-2012-OEM/dp/B0093CBTOM/
Switch $66: http://www.ebay.com/itm/DELL-POWERCONNECT-2716-USED-/251627465136?pt=US_Network_Switches&hash=item3a962a69b0
Firewall $90: http://www.amazon.com/EdgeRouter-ERLite-3-512MB-Ethernet-Router/dp/B00CPRVF5K/
Rack Screws $27: http://www.amazon.com/Tripp-Lite-SRCAGENUTS-Enclosure-Hardware/dp/B001DW8J5C/
Drive Converter $15: http://www.amazon.com/Icy-Dock-EZConvert-2-5-Inch-Converter/dp/B002Z2QDNE/

That is the full setup from the rack down to the software licenses that runs 144GB RAM and 4TB usable drive space on ZFS with a 128GB SSD Read cache. It falls short of $4k. We use XenServer and OpenIndiana.

That's only two VM servers, but every VM the client needs can easily run on one in case of a failure. Just thought I would share this setup to show that it is feasible to price a VM cluster out at under 6k. This is not the cheapest build I've done, but definitely near it and much smaller than I would recommend for most people. It is actually smaller than I recommended for this client, but it is what it is.

We always used these in the datacenter I was in:

ICY DOCK 2.5" to 3.5" SAS / SATA HDD & SSD Converter

Whatever drive you get, if you are getting a 2.5" and need it to fit in your iMac make sure you buy a Icy Box, other adaptors or brackets will mean that your connectors are too far from the drive or the screw holes and mounting points won't match up. The Icy Box will make sure its identical to a 3.5" drive.

Source: Having to open my computer up 3 times to try and get the right fit! Not fun!