Retina MBP SDXC Reader Info

Rofflesaurrr

macrumors newbie
Original poster
May 2, 2012
12
0
Just in case anyone else was wondering...

The integrated SDXC card reader on the new MBP is USB 3.0 enabled. The Intel HM77 provides 4 USB 3.0 ports. 3 are external, the 4th is used by the reader. I got read speeds of 77MB/sec with a Sandisk Extreme 95MB/sec card.

I'm going to purchase a rMBP online, but I could not find any info on what bus the card reader was running on, so I went to Bestbuy to find out. :)
 

innerpurpose1

macrumors newbie
Jun 14, 2012
7
1
Oakland, CA
Does this mean that one can use a SDXC card on the new MBP Retina and have comparable speeds to the internal flash drive? I'm wanting to put pics and music on the card and get a 256gb drive instead of spending the extra money for the 500gb drive.
Thanks for the help!
Graham
 

Rofflesaurrr

macrumors newbie
Original poster
May 2, 2012
12
0
Does this mean that one can use a SDXC card on the new MBP Retina and have comparable speeds to the internal flash drive? I'm wanting to put pics and music on the card and get a 256gb drive instead of spending the extra money for the 500gb drive.
Thanks for the help!
Graham
The SSD in the new Retina Macbook Pro averages speeds of 400-500MB/sec. The best SDXC cards only achieve read speeds of around 100MB/sec at most. Write speeds can be slower. However, a SDXC card on a USB 3.0 reader will usually have better overall performance than a conventional 2.5" internal hard drive. So yes, you could put pictures and music on the card and use it as a secondary storage media. I just wouldn't reccomend it if you're going to be doing a lot of writing to the card. Choose a quality card like a Sandisk Extreme or Lexar Professional. Most of these cards use SLC NAND (more write cycles) and have better wear leveling algorithms.
 

JayMBP

macrumors regular
Apr 25, 2011
152
21
Surrey, BC
I'm actually having problem with my rMBP's reader.

It seems to top at 20MB/s. And when I put the same card (Sandisk UHS-1 SDHC) in a USB3.0 reader, I get almost at the rated speed (45MB/s)

I'm getting some other SD cards next week and I will try them out.
 

terraphantm

macrumors 68040
Jun 27, 2009
3,742
557
Pennsylvania
I'm actually having problem with my rMBP's reader.

It seems to top at 20MB/s. And when I put the same card (Sandisk UHS-1 SDHC) in a USB3.0 reader, I get almost at the rated speed (45MB/s)

I'm getting some other SD cards next week and I will try them out.
The reader may be connected by USB 2.0 internally.
 

JayMBP

macrumors regular
Apr 25, 2011
152
21
Surrey, BC
The reader may be connected by USB 2.0 internally.
So, are different rMBP having different routing?

On Anandtech's test, they clearly showed that the reader was capable of handling speeds near 100MB/s

On a further checking to system info, it shows the reader is "2.5GT/s".

I'm assuming that the card reader is connected to the PCI-E bus directly hence the use of "GT/s"?
 

terraphantm

macrumors 68040
Jun 27, 2009
3,742
557
Pennsylvania
So, are different rMBP having different routing?

On Anandtech's test, they clearly showed that the reader was capable of handling speeds near 100MB/s

On a further checking to system info, it shows the reader is "2.5GT/s".

I'm assuming that the card reader is connected to the PCI-E bus directly hence the use of "GT/s"?
Okay, I didn't notice that part of anandtech's review, and I didn't have my laptop nearby to check. Not sure what to say then - I don't have any SD cards fast enough to test, nor do I have a USB 3.0 SD reader.

I don't know if it's connected directly to the PCIe bus though. I kinda doubt it. The IvyBridge CPUs have 16 lanes total. 8 of them are going to the GT 650M, and 8 of them are split between the two thunderbolt ports. That doesn't leave any PCIe lanes for other peripherals.
 

Tobias Funke

macrumors 6502a
Apr 3, 2012
628
61
I don't know if it's connected directly to the PCIe bus though. I kinda doubt it.
What is the maximum speed that my computer can use when reading and writing to an SD card in the SD card slot?

Macs that use the USB bus to communicate with the SD card slot have a maximum speed of up to 480 Mbit/s.

Newer Macs use the PCIe bus to communicate with the SD card slot and can transfer data at a much faster rate.

Determine the maximum speed of your Mac using the System Profiler:

1. Choose About this Mac from the Apple () menu.
2. Click More Info.
1. Select USB from the hardware section (for Macs that use the USB bus to communicate with the SD card slot).
2. Select Internal Memory Card Reader and look for the Speed entry.
or
1. Select Card Reader from the Hardware section (for Macs that use the PCIe bus to communicate with the SD card slot).
2. Look for the Link Speed entry. Computers that use the PCIe bus express their speed as GT/s.

From Apple website.

CLICKY
 

terraphantm

macrumors 68040
Jun 27, 2009
3,742
557
Pennsylvania
What is the maximum speed that my computer can use when reading and writing to an SD card in the SD card slot?

Macs that use the USB bus to communicate with the SD card slot have a maximum speed of up to 480 Mbit/s.

Newer Macs use the PCIe bus to communicate with the SD card slot and can transfer data at a much faster rate.

Determine the maximum speed of your Mac using the System Profiler:

1. Choose About this Mac from the Apple () menu.
2. Click More Info.
1. Select USB from the hardware section (for Macs that use the USB bus to communicate with the SD card slot).
2. Select Internal Memory Card Reader and look for the Speed entry.
or
1. Select Card Reader from the Hardware section (for Macs that use the PCIe bus to communicate with the SD card slot).
2. Look for the Link Speed entry. Computers that use the PCIe bus express their speed as GT/s.

From Apple website.

CLICKY
Hmm, I guess there must be an extra PCIe controller somewhere in there. Or apple is somehow able to use some circuitry to turn 1 PCIe 3.0 lane into 4 PCIe 1.0 lanes. Or something along those lines.
 
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Rofflesaurrr

macrumors newbie
Original poster
May 2, 2012
12
0
Hmm, I guess there must be an extra PCIe controller somewhere in there. Or apple is somehow able to use some circuitry to turn 1 PCIe 3.0 lane into 4 PCIe 1.0 lanes. Or something along those lines.
All 3 USB 3.0 ports and the card reader are connected to the same xHCI which has a 2.5GT/s link to the PCH. The USB 3.0 controller is now integrated into the PCH. It is not a separate 3rd party controller connected via a PCIe port. The Intel HM77 PCH also does not contain any PCIe 3.0 lanes. The only PCIe 3.0 lanes are provided by the CPU itself for the GT650M graphics and Thunderbolt.
 
Last edited:

Marx55

macrumors 68000
Jan 1, 2005
1,723
551
The maximum speed is the lowest between the bus and the reader. The bus may be great, but if the reader does not deliver, the latter is the maximum speed. Someone has real-world tests?
 
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