Transfer speed of SATA2 on PCI-Express

By TheOnlyRick ·
Hi - This one's for any hardware guys out there...

I recently installed a PCI-Express SATA card, it says it's 3GB/s. I also have onboard SATA (which I thought was the old SATA v.1 - 1.5GB/s)

Copying a 4 GB file to an internal PATA drive took 2 minutes using the onboard SATA. Using the PCI-e SATA card, it took five minutes-ish (and the progress bar was all over the place).

Is this typical? Even if they were the same SATA version, I wouldn't expect the PCIe card to take twice as long as the onboard SATA controller.

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Further to travel ...

by OldER Mycroft In reply to Transfer speed of SATA2 o ...

PCI-E is on the periphery of the circuitry, hanging off the edge of the motherboard, whereas the on-board controller is closer to the bus.

What you also have to take into account (but haven't mentioned as yet..) is the read/write speeds and the rotational speeds of the hard drives in question - the SATA is only (as it was touted at its launch "a wire replacement for an old serial connector") capable of up to 3Gb [Gigabits], not 3GB [Gigabytes].

If as you say, the progress bar was "all over the place", I'd be tempted to inquire what else the system was doing simultaneously since clearly the system-estimated duration kept adjusting to some sort of change in cycle priority.

*I think THIS rather sums up what I was trying to blurt out in my usual Scottish brogue:

For mechanical hard drives, SATA 3 Gbit/s transfer rate is expected to satisfy drive throughput requirements for some time, as the fastest mechanical drives barely saturate a SATA 1.5 Gbit/s link. A SATA data cable rated for 1.5 Gbit/s will handle current mechanical drives without any loss of sustained and burst data transfer performance. However, high-performance flash drives are approaching SATA 3 Gbit/s transfer rate.

Excerpt from:

In other words, just because you've got a 3Gb interface, doesn't mean you've got that capability in your hard drives.

..wait for TheChas to come along and **** me right out of the water.

Edit for *

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So, in summary...

by TheOnlyRick In reply to Further to travel ;) .. ...

MacSedroom - thanks for your reply.

The only equipment that changed in the set-up was the SATA connector, from onboard to PCIe.

Nothing else changed (the PC/mobo, the other hard drive, the other HD's connector)

So, because it's further from the bus, PCI-e will be slower than onboard SATA. Shame. I guess I didn't need to buy that SATA card.

Hmmmm... anyone wanna buy a PCI-e SATA card? One careful owner...

Oh yeah - I think I just had an instance of Firefox running when I was doing the transfer, (as well as an AV and antispyware app running in the background, and a couple of smaller apps as well.)



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The 'other apps' would've been enough ...

by OldER Mycroft In reply to So, in summary...

To prevent you from doing a clinical diagnostic comparison. The background tasks running in each instance (with / without the PCIe SATA) could not possibly be guaranteed to have been exactly the same.

I've always considered the PCIe function to excel when data is LEAVING the motherboard (one way only).

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by TheOnlyRick In reply to The 'other apps' would've ...

The other apps probably had a combined memory footprint of a meg or so, with minimal network traffic. They (surely?) wouldn't have been responsible for PCIe to take about three times as long as onboard SATA...

I accept that in some ways, a comparison should be as clean as possible (ie by removing extraneous factors).

When this doesn't hold true is when the comparison is on your PC with your apps on it. That's when you want the extraneous factors (ie the apps you use).

Cheers again,


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by TheOnlyRick In reply to Transfer speed of SATA2 o ...

I repeated the tests - this the transfer speeds were only a shade quicker on the onboard SATA (2 mins 55) than PCIe SATA (3 minutes).

I guess I've got my answer then: PCIe can be about the same (at best), but can also be much worse...



PS - Did you like the name 'MacSedroom'?

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The implied pseudonym was amusing ...

by OldER Mycroft In reply to Pah!

Yes - I did like it - wish I'd thought of it first (like maybe 2 years ago).

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