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SSD performance slower if HDD is being used at same time

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August 15, 2011 1:02:04 AM

Hello,
I've a ASUS M4A79 Deluxe motherboard that have the AMD Southbridge 750.
I've a Samsung SSD 470 64 GB connected to SATA port 1, a Seagate 1 TB in SATA 2 and a Seagate 160 GB in SATA 3 port. Finally in port 5 I've a DVDRW device.
The SSD plus the two HDD are running in AHCI mode while DVDRW in legacy ATA mode for a better compatibility.
System is very quick and responsive however if I'm doing an intensive work in my 1 TB HDD (like defragmenting it or loading a OS in VMware), the SSD performance is affected too.
If I'm defragmenting 1 TB HDD, programs like Firefox and others load slower (these programs are in my SSD).
To test this behavior I ran a defragmentation in 1 TB while I tested AS SSD benchmark. Altough sequential read speed (260 MB/S) and write speed (150 MB/S) were the same as without activity in secondary HDD, the access time was higher.
While defragmenting Seagate, SSD read access time was 1,2 ms vs 0,2 ms and write access time was 0,9 ms vs 0,1 ms.
Is normal that performance of my SSD drop when the other SATA port device is being used hard? Is that because the SATA controller is more "stressed"?
CPU activity was all time below 10%.

Thanks.

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a c 523 G Storage
August 15, 2011 8:08:01 PM

andregoujon said:
Is normal that performance of my SSD drop when the other SATA port device is being used hard? Is that because the SATA controller is more "stressed"?


Yes, I believe that is the performance limitation of the AMD SB750 chipset.

You should be able to increase your SSD performance by increasing the voltage to the South Bridge controller, but I don't know much about overclocking so you'll have to do some research on how to do it.

Also, updating your AMD South Bridge & AHCI drivers to the latest version may improve performance.
Here's the link: http://support.amd.com/us/gpudownload/windows/Pages/rai...

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August 19, 2011 3:20:45 AM

Best answer selected by andregoujon.
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August 19, 2011 3:21:52 AM

Thanks. I suspected it was because my chipset is a little old.
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