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HDD to SSD upgrade: Intel P55 limitation, how to proceed?

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June 7, 2011 3:11:59 PM

Hi all. I will soon be upgrading from HDD to SSD for my OS drive. While I know that any SSD will absolutely smoke a traditional hard drive in terms of speeds, I do have a question.

I have a Gigabyte P55 motherboard... six SATA II 3 GB/s ports (running off P55 chipset) and two SATA III 6 GB/s ports (running off Marvell 9128 chipset). I researched it up, and that Marvell controller runs off a PCI Express 1x lane on the Intel P55 (the Block Diagram in my motherboard manual confirms this).

Furthermore, research shows that the P55's PCI Express 2.0 lanes actually only run at PCI Express 1.0 speeds. The P67 is where they started operating at proper 2.0 speeds (and P67 is where they started adding SATA III ports running off the CPU, too)

If plugged into SATA III ports, this literally limits the speed of any SSD to 250 MB/sec, since that is the max speed of a PCIE 1.0 1x lane, although thats just the theoretical max. Online hardware testing sites say the P55 on a Marvell chip is limited to about 195 MB/sec.

I built this PC early in 2010 and I dont plan to build a new PC for quite a while. Many performance-class SATA III SSDs are surpassing 500 MB/sec in both read/write ...do I have any option to get anywhere near that?!

The only option I could think of is the OCZ Revodrive, which runs off a PCI Express 4x lane (I have a second 16x slot running at 4x). Since mine only run at half-speed, 4x PCI Express 1.0 is still 8 Gbit/sec, which would be plenty fast enough and remove the bottleneck.

The block diagram for my motherboard clearly shows the primary 16x slot on my mobo (which my GPU is connected to) is connected directly off the LGA 1156 CPU, while any remaining PCI Express slots are running off the P55, so I wouldn't be splitting the lanes and reducing GPU or drive performance.

Other than getting a Revodrive, do I have any other option?

Thanks in advance!

~ Chris

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a c 415 G Storage
June 7, 2011 4:31:18 PM

I doubt you'd see a whole lot of difference in practical wall-clock time between a drive running at 250MByte/sec and 500MByte/sec because most of the performance improvement you get from an SSD doesn't come from it's fast transfer rate, but rather from it's very fast access times (which aren't affected by the transfer rate limitation).

But if you're really keen on getting true SATA-III speeds my advice would be to look for a SATA-III to PCIe adapter card to plug into one of your motherboard slots, and then connect the SSD to it.
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June 14, 2011 2:15:59 AM

Best answer selected by crumbworks.
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