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Luba

macrumors 68000
Original poster
Apr 22, 2009
1,819
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MacPerformanceGuide.com recommends installing SSD in the 2nd optical bay drive right below the SuperDrive without need to secure (mount/screw it in) it.

Read a review by Wavy Dave on Amazon and he doesn't recommend installing SSD in the optical bay even though it has a SATA connector because it's not a "primary" SATA connector. Is that true, our optical bay SATA connector is not primary??

I currently have all 4 bays filled with HDDs so would rather install the X-25M 160 GB below the SuperDrive.
 
Read a review by Wavy Dave on Amazon and he doesn't recommend installing SSD in the optical bay even though it has a SATA connector because it's not a "primary" SATA connector. Is that true, our optical bay SATA connector is not primary??

I currently have all 4 bays filled with HDDs so would rather install the X-25M 160 GB below the SuperDrive.

Whoever that dude is, he apparently has no idea what he's talking about.

All SATA ports of the Mac Pro are completely equal to each other, with the little exception that the four that are directly soldered on to the motherboard (the four sled ports) can be directly used with Apple's RAID card.

The ICH10 chipset does not separate between "primary" and secondary ports.

A lot of people run SSDs on the optical bay, including myself.
I've got a 160GB Intel G2 in the lower bay and it runs absolutely great. No problems or slowdowns compared to the "primary" :)rolleyes:) ports whatsoever.
Just go for it.
 
Whoever that dude is, he apparently has no idea what he's talking about.

All SATA ports of the Mac Pro are completely equal to each other, with the little exception that the four that are directly soldered on to the motherboard (the four sled ports) can be directly used with Apple's RAID card.

The ICH10 chipset does not separate between "primary" and secondary ports.

A lot of people run SSDs on the optical bay, including myself.
I've got a 160GB Intel G2 in the lower bay and it runs absolutely great. No problems or slowdowns compared to the "primary" :)rolleyes:) ports whatsoever.
Just go for it.
It might be a result of confusion as to how the SATA ports are implemented in the ICH (4 + 2 configuration, where the group of 4 is the HDD bays, and the remaining pair are the ODD ports).

They are all technically 3.0Gb/s SATA, so in a port by port comparison, are equal in terms of throughputs. The DMI/ESB2 bus used to carry the data OTOH has limitations (1GB/s up or down), and the SATA ports (as a whole) are limited to ~660MB/s (below what 6x ports can actually push flat out, running simultaneously ~1650MB/s). So it's about 1GB/s short. :eek:
 
Just to clarify what you're saying, are you saying: The ODD SATA ports are just as fast as the HDD SATA ports, so no problem there. I can go ahead and install a SSD in the lower optical bay and not lose out on any speed.

BTW, do you see any need to secure, perhaps use tape, to tape down the SSD in the lower optical bay?

But you're thinking that Wavy Dave (the dude :) who posted a review on Amazon) might have gotten things mixed up by bringing up a non-existent "primary versus secondary" SATA speed difference with DMI/ESB2 bus limitations? The limitation being all SATA ports in use at the same time is limited to 660MB/s (110MB/s per SATA port), but individually each SATA port can go up to ~275 MB/s (1650MB/s divided by 6)?

Thanks everybody in answering my question!


It might be a result of confusion as to how the SATA ports are implemented in the ICH (4 + 2 configuration, where the group of 4 is the HDD bays, and the remaining pair are the ODD ports).

They are all technically 3.0Gb/s SATA, so in a port by port comparison, are equal in terms of throughputs. The DMI/ESB2 bus used to carry the data OTOH has limitations (1GB/s up or down), and the SATA ports (as a whole) are limited to ~660MB/s (below what 6x ports can actually push flat out, running simultaneously ~1650MB/s). So it's about 1GB/s short. :eek:
 
If you want, there are a plenty of solutions to securely install SSDs or HDDs in the optical bay. They are not cheap, but most are very elegant.

I boot from my ODD SATA ports with no complaints and blazing speed.
 
Hello,

There are very very cheap ways to mount any 2.5 disks (including SSDs) in the empty optical bay. Digilloyd just lets them hang because 1) he doesn't know about the 5$ solution, or 2) he can't talk about it because he's glued to the hip with his sponsor (that doesn't sell that 5$ solution).

http://www.xpcgear.com/scythe-2-5-to-5-25-bay-rafter.html

Xpc gear sells it for 9$, but I managed to find it for 5$ in Canada.

Enjoy a cheap way to securely mount your SSD in your optical bay.

Loa
 
I have a fifth HD in the optical bay. I just have it sitting at an angle with one screw in it. (Only one screw hole will ever line up without using a bracket)

It's enough to stop it sliding about as I tilt the machine to access the side.
 
Just to clarify what you're saying, are you saying: The ODD SATA ports are just as fast as the HDD SATA ports, so no problem there. I can go ahead and install a SSD in the lower optical bay and not lose out on any speed.
Only under 2x conditions would you have a loss in throuhput:
1. You exceed the bandwidth capable of the ICH (simultaneous access, all drives are 3.0Gb/s).

2. Use of a newer SSD that utilizes a 6.0Gb/s SATA port, as the ICH is only 3.0Gb/s (and there are reports that it does matter, even though the max throughput of the drive is still technically possible on 3.0Gb/s ports, as it's missing the optimizations that were added to the newer spec).

BTW, do you see any need to secure, perhaps use tape, to tape down the SSD in the lower optical bay?
Some have left them unsecured. So it's up to you, if you want to do this or not. But there are inexpensive ways to do it, such as the 3x 2.5" drives in a single 5.25" bay Rafter by Scythe (~$9USD last I saw).

But you're thinking that Wavy Dave (the dude :) who posted a review on Amazon) might have gotten things mixed up by bringing up a non-existent "primary versus secondary" SATA speed difference with DMI/ESB2 bus limitations? The limitation being all SATA ports in use at the same time is limited to 660MB/s (110MB/s per SATA port), but individually each SATA port can go up to ~275 MB/s (1650MB/s divided by 6)?
Yes. Real world performance is ~270 - 275MB/s, vs. a theoretical max throughput of 375MB/s per port.
 
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