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Sata 3.0 Gb/s running only at UDMA-6 ?!

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October 23, 2007 3:09:03 PM

Hello everyone,

I have the Asus M2N32-SLI deluxe wireless motherboard (nForce 590),

it has the Silicon Image SiI 3132 SATALink Controller,

when I check Windows Control panel under Silicon Image Sata Controller
it does not list any device info (only Host Link Speed: 3.0 Gb/s and Device Link Speed: 1.5 Gb/s), neither anything in the Flash BIOS tab...

In device manager I's indicated that NVIDIA nForce 590 Serial ATA Controller is set to 3.0Gb/s,
speed test values:
Theretical limit: 300.0
Burst speed: 171.4
Sustained speed: 59.4

HD Tune indicates:
Standard: SATA II
Supported UDMA Mode 6
Active: UDMA Mode 6

so my hard drive isn't being used to it's full potential? or is SATA 3.0 Gb/s such a rip-off (only 170 !) ???
(I've installed latest Asus drivers)

my hard drive is a Seagate ST3500641AS, 16MB buffer, Sata 3.0Gb/s,

I have Windows Xp pro and the x64 version (both same results),

anyone any info?

many thanks in advance,

take care!

Kind regards,
Michael

More about : sata running udma

October 23, 2007 3:24:40 PM

Everything looks fine to me, I don't see the issue? You're sustaining 60MB/s at the maximum supported UDMA mode, what's the problem?
October 23, 2007 3:30:20 PM

I think that the OP was expecting to see a transfer at 300 MB/s. This of course is not possible.

If there were drives capable of that then we would have a faster interface so as to be sure that the interface is not the bottleneck.
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October 24, 2007 5:48:37 PM

so SATA 3.0 Gb/s means only around 170 Mb/s in practice?

so why do they call it 300 Mb/s ?

October 24, 2007 9:37:47 PM

SATA300 (3.0 Gb/sec, or 300 MB/sec), is the speed rating of the interface. In other words, the cable and the SATA controller can do UP TO 300 MB/sec. Actual speed depends on the device that is attached. Your hard drive is capable of 170 MB/sec burst, and 60 MB/sec sustained transfer rate. That is the speed you will get.

It's just like a fire hose. A 2.5 inch fire hose can supply about 500 gallons per minute. But if you hook it up to a pump that can only pump 200 gallons per minute, then that's all you get.
January 4, 2008 5:12:35 PM

I posted this elsewhere on tom's forums:

Wow. Theres a lot of erroneous info here..hope mine isnt...correct me if im wrong.

Your mobo's host controller has a a list of supported UDMA modes and so does your HD(yours is UDMA7 aka SATA 150). At power-on, the UDMA mode is negotiated between the devices and is supposed to be set the UDMA mode to the highest common mode. So my guess would be that your mobo is old and can only support to UDMA5 or, less likely, you have some incorrect configuration.

As for 1.5Gbps and 3.0Gbps speeds...these refer to the line speed between the drive's controller and the host controller. 1.5Gbps * (1024Mbps/Gbps) / (8b/B) = 192MBps theoretical maximum, but even running at UDMA7/"SATA150" the theoretical limit is 169MBps. I think it is used a marketing gimmick, but also the reality is that these two are different technology specs, SATA and ATA/ATAPI(where UDMA is defined).

If u need something to read, head over to t13.org and look up the ATA7 or ATA8 Spec. I think the SATA spec is avaliable only to more priveleged persons.
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