Two options for where to install an SSD: What's the difference?

Riku7

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Original poster
Feb 18, 2014
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I have a classic Mac Pro flashed to 5,1, bought from a refurbisher who put it together for me. It's my first properly modifiable computer so I'm not yet extremely familiar with its internal architecture.
I have the OS installed onto an SSD which I believe replaces the area where the other CD drive would be. The other drive on the other hand, works as a normal CD drive. In the sled bays, I have two HDDs for storage. I've been handling the HDDs but the SSD is hidden from view and I've never opened that part of the Mac.

I've been trying to make sense of the hard drive business but all the abbreviations just look like a big mess.
Apparently there are these OWC made sleds that allow an SSD to be installed to one of the vacant sleds just like the HDDs are right now, am I right?

What is the difference of installing a SSD to a bay using an SSD adapter sled, vs. installing it to the place of a CD drive? It's easy to find tutorials on how to do these things, but I want to know why you would do one or the other.

My primary use for now would be to also get the Bootcamp Windows onto its own SSD so it wouldn't have to be on a partition of a poor old HDD.
 

MagicWok

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Mar 2, 2006
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To help with some of it. Yes you can get drive sleds that work with the backplane of the Mac Pro. Bear in mind that because of the backplane set up, not all 2.5" drive adaptors will work. I ordered two of these from Amazon (UK), they worked absolutely fine and are cheaper than the OWC variants.

There isn't any speed difference between the two options (sleds versus DVD drive slot). They all are at SATA2 speeds.

You can get PCI-e SSD adaptors that enable you to run at SATA3 speeds, if you need it of course.
 

JedNZ

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Dec 6, 2015
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Deep South
As far as I'm aware, there is possibly no difference between installing a SSD in one of the optical bay drives versus the direct connect bays. If you go for the direct connect bay option then it's slightly easier to remove the drive by pulling out the sled, versus having to pull the optical compartment out, and juggle with it to unplug the power and SATA cable.

Boot-up order
I'm not sure what the boot order is if a startup device hasn't been selected, like after you do a reset PRAM and I clears out the startup disk. Not sure if it scans the optical bays first before the direct connect bays, or vice versa. Does it scan direct connect bay 1, then 2 etc? Maybe someone else can answer that one.

Windows install
I did encounter an issue when I originally tried to install Windows (from a DVD) on a SSD in the spare optical drive bay. It simply would not see it. I even removed all my other Mac (HFS+) formatted drives, and still no luck. So I moved the SSD (for Windows) to direct connect bay 1 and had no issues after that (the key was not to have any other HFS+ formatted drives attached or installed anywhere else).

Sleds versus adapters
The (OWC) sleds for installing a SSD into a direct connect bay are great. I use one of these (for my Windows bootcamp SSD), plus I also use a Newertech AdaptaDrive for a 2.5" spinner. The difference between the sled and the adapter is you attach the SSD directly to the OWC sled, versus attaching the SSD to the AdaptaDrive which in turn screws into a normal drive sled.

I have Windows on a Samsung 850 EVO and it runs exceptionally well. Just installed Rise of the Tomb Raider today and it runs perfectly - saves me having to upgrade my macOS to High Sierra to run it on the Mac side.
 

kschendel

macrumors 65816
Dec 9, 2014
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Pretty much any 3.5 to 2.5 adapter that includes an electrical connection adapter (such as many of the Icy Dock units, or the one linked by MagicWok) will work fine for mounting an SSD in one of the drive bays. The adapters that are just mounting plates without a connector are less likely to work.

If you install SSD into a drive bay or the CD/DVD bays you'll get SATA 2 speeds. Generally speaking, pretty much any SATA 2 or 3 SSD will work, and there is generally no point in buying a more expensive / faster benchmarked SSD because you'll be limited by the SATA 2 speed anyway.

For SATA 3 you need a PCIe card that includes a SATA 3 controller. (so, not one of the $20 cards which are just mounting adapters.) Even though SATA 3 is theoretically double the transfer speed, I doubt that you'll see a big difference in practice, for most applications. There will be exceptions of course.

If you want maximum speed you'll want to move to a PCIe SSD. These are non-SATA SSD's that typically use the m.2 form factor, and can be mounted in one of those inexpensive PCIe cards. PCIe SSD's talk either the NVMe or AHCI protocols; the former is non-bootable in the cMP and can only be used with High Sierra. (or linux, and I imagine Windows.) The AHCI SSD's can be booted from but they are becoming increasingly difficult to find. PCIe SSD's can post garish benchmark numbers, but again, you may not see any real world difference unless you are doing massive amounts of I/O.
 
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h9826790

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Apr 3, 2014
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I have a classic Mac Pro flashed to 5,1, bought from a refurbisher who put it together for me. It's my first properly modifiable computer so I'm not yet extremely familiar with its internal architecture.
I have the OS installed onto an SSD which I believe replaces the area where the other CD drive would be. The other drive on the other hand, works as a normal CD drive. In the sled bays, I have two HDDs for storage. I've been handling the HDDs but the SSD is hidden from view and I've never opened that part of the Mac.

I've been trying to make sense of the hard drive business but all the abbreviations just look like a big mess.
Apparently there are these OWC made sleds that allow an SSD to be installed to one of the vacant sleds just like the HDDs are right now, am I right?

What is the difference of installing a SSD to a bay using an SSD adapter sled, vs. installing it to the place of a CD drive? It's easy to find tutorials on how to do these things, but I want to know why you would do one or the other.

My primary use for now would be to also get the Bootcamp Windows onto its own SSD so it wouldn't have to be on a partition of a poor old HDD.
I have a Windows 10 SSD installed in the optical bay SATA port now. Before that, it's installed in bay 1. In my case, it can always boot.

And when I install it in bay 1. I simply remove its case and plug the SSD into the slot without any adaptor.
SSD SATA port.jpg


Zero cost, zero issue. I know some guys put a rubber band on the stock sled to give the SSD a little bit support, and install the SSD without removing the case.

I also know a guy who just plug the whole 2.5" SSD into the slot with zero extra support. And it's been 5 years now, his cMP still working. So, obviously the SATA port itself is strong enough to support the SSD.

But if you really want an adaptor. I believe most simple low cost adaptor can do the tricks.
 

XNorth

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Feb 23, 2018
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What is the difference of installing a SSD to a bay using an SSD adapter sled, vs. installing it to the place of a CD drive
The short answer is there is really no difference. 2.5" SATA SSDs can be used in both. The optical (CD/DVD) drive bay and the four HDD sled bay slots all have the SATA 2 interface, with the same transfer rate of up to 300MB/s.

The difference is in the form factor of each bay. The HDD slots were designed to hold a 3.5" HHD securely, so using a sled adapter, it's painless to install a 2.5" SSD.

The optical drive bay was designed for 5.25" internal optical drives and is more of a challenge if you want to securely install an SSD in place of the DVD drive with something better than electrical tape. I solve the problem with a mod: a 5.25" enclosure for 2.5" SSDS, RAIDed 0.
 
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h9826790

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The short answer is there is really no difference. 2.5" SATA SSDs can be used in both. The optical (CD/DVD) drive bay and the four HDD sled bay slots all have the SATA 2 interface, with the same transfer rate of up to 300MB/s.

The difference is in the form factor of each bay. The HDD slots were designed to hold a 3.5" HHD securely, so using a sled adapter, it's painless to install a 2.5" SSD.

The optical drive bay was designed for 5.25" internal optical drives and is more of a challenge if you want to securely install an SSD in place of the DVD drive with something better than electrical tape. I solve the problem with a mod: a 5.25" enclosure for 2.5" SSDS, RAIDed 0.
IMO, just let the 2.5" SSD sit inside the optical bay is fine. There is no moving parts in there, nothing really need to be secured.
IMG_4245_filtered.jpg

And it's easier to install the SSD in optical bay in this way, because no adaptor required to hold the SSD in place, and no stress will be given to the SATA port.
 
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macuser453787

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May 19, 2012
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Galatians 3:13-14
I want to know why you would do one or the other
There are many reasons why, and maybe one big reason is that at some point cMP modders needed room for an SSD because the 4 drive bays were already occupied with other hard drives. Other reasons may have been: just for fun, or just because they could.

It may be that the reasons why are as numerous as the number of people who have done it.

But one way or another, the why is because of an actual or perceived necessity or desire to do so. :)
 
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lowendlinux

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Sep 24, 2014
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I have two optical drives so my OSX drive is on an OWC Accelsior S, my scratch drive is 128GB MBA drive on a Sintech card, my W10 drive is an SSD on an OWC sled in bay 1, bay 2 and 3 are a pair of raided 2TB spinners, and bay 4 is a 6TB time machine spinner.

We all have different needs, desires, and budgets and our storage layout will reflect that
 

XNorth

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Feb 23, 2018
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I want to know why you would do one or the other.
I'm using all SSDs because I want the fastest storage and system drives currently possible for the cMP SATA 2 interfaces. I don't need the old Mac, but want to extend its longevity and keep it up to date as much as I can.

I removed the DVD drive and have modded the optical bay for an SSD PCIe RAID enclosure, for 800+ MB/s throughput. Two of the HDD slots house a SSD RAID for OS 10.13.4, good for 500+ MB/s. The third HDD slot has a spinner HD for updating and cloning the OS. The 4th HDD slot is empty to provide easy access to the PCIe cards.
 

kohlson

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Apr 23, 2010
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SSDs can go any of three places, and the why for each depends on what you want to do (that is, how you want to configure your CMP), and what you have at hand.
Optical Bay: easiest/cheapest, imho. Though you need to wiggle some things in opening up this bay. But really, just connect up your SSD at you're good to go. If you want to "mount" it consider a small reverse-loop of duct tape. Remember, SSDs have no moving parts and are generally resistant to shock/vibration. Mine lived there for a few years.

- Disk Bay: You can do what H98 suggests. Or you can buy a special sled. Side note: While the original sleds work for many HDDs, new, larger HDDs have mounting holes in different places. So you will need a different sled when using those.

- PCIe bus: Capable of faster I/O, but not really for a 2.5-inch packaged SSD. If you don't know if you need faster disk I/O, you likely do not. Note that for generalized use there appears to be no performance difference in an 2.5-inch SSD mounted in any of these locations.

So why? cMP offers configurability. If you need 5HDDs and optical drive, put an SSD on PCie. If you filled up you PCIe slots, put on SATA. And so on.
 
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DPUser

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Jan 17, 2012
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I have four SSDs sitting in the optical bay... after moving the optical drive to the lower bay, it serves nicely as an SSD shelf.

Two SSDs are connected to the two optical ports. Two more are connected via longer SATA cables to a PCIe SATA3 card. Power for the SSDs is derived from one of the optical bay power ports split three ways via an adaptor. In order to allow the power adaptor to be used, I disconnected the SATA data part of that optical bay cable from the backplane board and replaced it with a standard SATA data cable run back to the optical bay.

As my Mac Pro sits quietly and stationary in an air-conditioned machine closet, all is well.
 

Riku7

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Original poster
Feb 18, 2014
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Wow I thought I had replied but apparently I wrote it but didn’t post.
Thank you all for your input.

...I ordered two of these from Amazon (UK), they worked absolutely fine and are cheaper than the OWC variants...
Excellent, any European resellers will work out for me. I’ll bookmark that link.

..Boot-up order
Windows install..
Boot-up order: If after resetting PRAM I start with alt pressed, will it solve this?
And of course under normal conditions when no resetting has been done, the computer just boots from whichever disk you’ve chosen to be it?
Recently I discovered a way of restarting the computer to boot to Windows but “only this once”. I saved it as an AppleScript in the script menu so now I don’t need to ever touch the boot disk settings, I just run the script that boots to Windows, and when I shut down Windows, it will automatically boot to Mac the next time. (This sucks when you’re doing stupid Windows stuff when Windows has to be restarted...)

Your Windows installation experience is valuable information. If that’s what tends to happen, it definitely suggests that I should go straight for the bay option.

...PCIe bus: Capable of faster I/O, but not really for a 2.5-inch packaged SSD. If you don't know if you need faster disk I/O, you likely do not. Note that for generalized use there appears to be no performance difference in an 2.5-inch SSD mounted in any of these locations...
(Many users mentioned this but) SATA 2 vs. 3 speeds: What do you mean by most applications / typical use etc.? What sort of user needs SATA 3?

...And when I install it in bay 1. I simply remove its case and plug the SSD into the slot without any adaptor...
Oh you can remove the case.. That’s just a circuit board then, it can’t be heavy. While I’m not concerned of its weight, I might be concerned of dust, actually; I’ve noticed that due to the surroundings that I’m in, the computer gets very dusty indeed and especially on the processor tray, I can’t seem to be able to remove all dust perfectly using compressed air, because the tiny components kind of have tiny sharp edges here and there, and dust gets stuck to them like wool to a needle. That was the condition when I bought this machine used, I’ve made it a habit to use compressed air a few times a year to avoid further buildup.

...I have four SSDs sitting in the optical bay...
That’s an interesting configuration. I’m trying to imagine it. The fan in the top of the machine, hidden (whatever that fan is called) is the loudest one, it sometimes resonates in a very annoying cycling manner and I have done all the tests to conclude that such resonance is not caused by any of the spinning drives; I can remove them all completely and still get that sound. It was hard to locate but I’m very confident now that it’s the one at the top. I wonder if you place 4 SSDs up there as well, how’s the heat?
 

h9826790

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Apr 3, 2014
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Hong Kong
Wow I thought I had replied but apparently I wrote it but didn’t post.
Thank you all for your input.


Excellent, any European resellers will work out for me. I’ll bookmark that link.


Boot-up order: If after resetting PRAM I start with alt pressed, will it solve this?
And of course under normal conditions when no resetting has been done, the computer just boots from whichever disk you’ve chosen to be it?
Recently I discovered a way of restarting the computer to boot to Windows but “only this once”. I saved it as an AppleScript in the script menu so now I don’t need to ever touch the boot disk settings, I just run the script that boots to Windows, and when I shut down Windows, it will automatically boot to Mac the next time. (This sucks when you’re doing stupid Windows stuff when Windows has to be restarted...)

Your Windows installation experience is valuable information. If that’s what tends to happen, it definitely suggests that I should go straight for the bay option.


(Many users mentioned this but) SATA 2 vs. 3 speeds: What do you mean by most applications / typical use etc.? What sort of user needs SATA 3?


Oh you can remove the case.. That’s just a circuit board then, it can’t be heavy. While I’m not concerned of its weight, I might be concerned of dust, actually; I’ve noticed that due to the surroundings that I’m in, the computer gets very dusty indeed and especially on the processor tray, I can’t seem to be able to remove all dust perfectly using compressed air, because the tiny components kind of have tiny sharp edges here and there, and dust gets stuck to them like wool to a needle. That was the condition when I bought this machine used, I’ve made it a habit to use compressed air a few times a year to avoid further buildup.


That’s an interesting configuration. I’m trying to imagine it. The fan in the top of the machine, hidden (whatever that fan is called) is the loudest one, it sometimes resonates in a very annoying cycling manner and I have done all the tests to conclude that such resonance is not caused by any of the spinning drives; I can remove them all completely and still get that sound. It was hard to locate but I’m very confident now that it’s the one at the top. I wonder if you place 4 SSDs up there as well, how’s the heat?
Don't know how bad your place would be. But I am also living in a very dusty city. If I didn't blow the dust for 2 weeks, the cMP will run at least 5C warmer. Every single time after I clean the dust, I can see the following effect.
NB dust clean.jpg

If you only need to clean it few times a year. I think the SSD can survive without any issue.
 

MikkelAD

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Feb 17, 2018
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kohlson

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Apr 23, 2010
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What do you mean by most applications / typical use etc.? What sort of user needs SATA 3?
General application - web, office apps, and so on. Disk performance is a combination of throughput (such as SATA 3 is 6Gbps) and IOPS. As noted, a cMP has SATA 2. Using an SSD makes a noticeable difference in performance, but not much, if any different for SATA 2 versus SATA 3.

Most apps don't come close to needing more throughput. But many on these forums have written of their need for PCIe cards with NVME RAID.
 

bsbeamer

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Sep 19, 2012
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- Single 2.5" SSD in Apricorn Velocity Solo x2 PCIe adapter (system drive) gets about 465MB/s write and 475MB/s read.
- Two 2.5" SSDs in Apricorn Velocity Duo x2 PCIe adapter get about 470MB/s write and 490MB/s read in non-RAID configuration (show as two separate drives).
- Single 2.5" SSDs in SATA sleds (non-RAID) get about 255MB/s write and 270MB/s read.
- Two 2.5" SSDs in SATA sleds configured in RAID-0 get about 435MB/s write and 515MB/s read.

All speeds above with AJA System Test Lite on authentic Mac Pro 5,1. SSDs reported are all various Samsung SSDs (840, 840 EVO, and 850 EVO) and all are 2.5" form factor.

There is no need for PCIe unless you need read/write speeds greater than the SATA sled can provide, OR need to add more drives to your system than SATA sleds available. Currently have 7 SSDs in my system - 4 via SATA sled and 3 via PCIe adapters. Depending on project(s), files are moved around between these internal SSDs and/or external RAIDs.
 

orph

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Dec 12, 2005
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iv got two SSD's in my 5.1 dvd drive bay just lose hanging out, no problems (osx install and win7 install).
there not special slots or plugs it's just mac pro has 6 SATA ports two in dvd bit and 4 in the main bit there not special or anything.

for most people just any normal branded SSD will be all they need, the speed changes tend to be small (say compared to the jump from a HD) and it's randoms that relay show the speed not read/write speed
Samsung have 5 year warranty which is nice
 
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crjackson2134

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Mar 6, 2013
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Charlotte, NC
Without reading this whole thread, I’m asking for some direction.

I need to add another SSD to the system and I’d like to use the option of adding a second SSD to my Apricorn Velocity Solo X2.

Can someone point me to the proper cable to do this on Amazon?I already have the 860 EVO in my cart. Just don’t know which cable to add.
 

Demigod Mac

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Apr 25, 2008
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Recently I discovered a way of restarting the computer to boot to Windows but “only this once”. I saved it as an AppleScript in the script menu so now I don’t need to ever touch the boot disk settings, I just run the script that boots to Windows, and when I shut down Windows, it will automatically boot to Mac the next time. (This sucks when you’re doing stupid Windows stuff when Windows has to be restarted...)
Would love to know how to do this! A handy utility called BootChamp performed this task but it stopped working with the introduction of SIP in 10.11 and as a result the author stopped updating it.
 

bsbeamer

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Sep 19, 2012
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Without reading this whole thread, I’m asking for some direction.

I need to add another SSD to the system and I’d like to use the option of adding a second SSD to my Apricorn Velocity Solo X2.

Can someone point me to the proper cable to do this on Amazon?I already have the 860 EVO in my cart. Just don’t know which cable to add.
Any standard SATA III cable (or lower spec) should work fine:
https://www.amazon.com/gp/aw/d/B018Y2LCEI/

You’ll need to provide power to the drive as well. According to the specs, the SATA on the Solo X2 does not provide power. Several ways to do this depending on setup.

You MIGHT be best setting up as a RAID with both drives on Solo X2 for best performance (not just random speed). Don’t remember if it was a suggestion or requirement. The firmware update years back may have changed that.
 

crjackson2134

macrumors 601
Mar 6, 2013
4,741
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Charlotte, NC
Any standard SATA III cable (or lower spec) should work fine:
https://www.amazon.com/gp/aw/d/B018Y2LCEI/

You’ll need to provide power to the drive as well. According to the specs, the SATA on the Solo X2 does not provide power. Several ways to do this depending on setup.

You MIGHT be best setting up as a RAID with both drives on Solo X2 for best performance (not just random speed). Don’t remember if it was a suggestion or requirement. The firmware update years back may have changed that.
Thanks for that. I have plenty of those cables laying around.

I won’t be doing a raid and I may end up putting it in a drive bay. It’s just going to be used as a bootable clone to my main install, since TM failed me when I needed it, I’ve moved to CCC and maintain a clone now but the drive I’m using is excruciatingly slow. If I have to start tapping power, it’s probably not worth the effort to set it up on the Solo x2.
 

bsbeamer

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Sep 19, 2012
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There are some splitter-style power cables which probably would work with the low power requirement of SSDs, but the drive bay is usually the easiest install for a spare SSD. There are a few threads with good photos and details on that install if you need them. Think @h9826790 specifically has a drive installed this way.
 
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