Nvidia 580 southbridge SATA controller capped at 100MB/sec?

omarja1

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May 11, 2001
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Hi!
I have a p5n32-SLI premium ASUS motherboard (NVIDIA 580 chipset), with a Core 2 Duo E6600, GeForce 8800GT and 2GB DDr2-800.
I have 2 300 GB SATA hard drivers in RAID0 mode.
I am running both Vista Ultimate x64 and WindowsXP Pro SP2 x86.
I recently got a third 300GB drive, and tried to set the three of them to RAID5. It worked, read speeds were ok, but write speed was terrible, at about 5MB/sec. This is completely unjustified, as the CPU was idle while copying files, and could certainly have been used for XOR calculations to speed up the writes. Is this the driver's fault?
Anyway, since 5MB write speed is unacceptable, I tryed RAID0 with 3 drives. To my surprise, performance was identical to having 2 drives in RAID0, peaking out at about 105MB/sec.
This suggests that the SATA controller is capped at around 100MB/sec, since adding additional drives didn't increase the speed. Also, I tried copying another file between two other independent hard drives at the same time, and the OVERALL speed, sum of the two file copies going on at the same time, was still 100MB/sec.
Is is really possible that a relatively modern motherboard has a SATA controller globally capped at 100MB/sec? This sounds crazy to me.
Has anyone else tryed such testes? Anyone got similar results?
I get the same stuff both under Vista and XP, which also leads me to believe it's actually a controller issue, and not a driver issue.
Any ideas? Comments?
Is there any solution to get high performance IO other then getting a $500+ professional RAID controller, that usually uses a PCI-e x4 slot, not available on my board? (and most boards for that matter).

Also, as a related issue, why aren't the extra x16 PCI-e slots in my mobo usable for things other than graphics card? I theory I should be able to plug a x4 or x8 SATA RAID card on one of those slots...


Thanks,
Omar
 

Joe_The_Dragon

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Sep 19, 2006
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x4 and x8 cards will work in a x16 slots and some boards some have x16 slots that only run it x4
 

omarja1

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May 11, 2001
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Are you sure? That's what I thought, but a friend at a computer store says these x16 slots, although you can physically fit a x4 or x8 card in them, will only work with graphics cards, independent of the fact that they actually only run at x8 or x4 speed. Also, my motherboard manual also says those slots (my board has 3 of them) are only usable for graphics cards... I guess I will have to try to find out... but it would suck to spend 400$$$ to find out the card does not work... Mobos with real x4 or x8 slots are hard to come by... I found a Supermicro one, but the rest of the features isn't that nice...
Omar