SATA III on a SATA II Motherboard Update

Ok so for those who may have read the last post on using a SATA III SSD on a SATA II motherboard, there was a niggling issue in my conclusion. I hadn’t actually tested the drive on the motherboard with the correct setting on the motherboard. I did try but got a BSOD (Blue Screen of Death) when booting.

I have been using the PC for a few years and had built it with RAID mode off – meaning that AHCI mode was emulated when the OS was installed. This is also known as legacy mode. It doesn’t support TRIM, although I am not entirely sure what else. It never affected me and I didn’t worry about it.

Here is my AS SSD Benchmark results with the SSD connected to the motherboard in this wrong legacy mode:

SATA III on a SATA II M/B in Legacy Mode  

SATA III SSD connected to SATA II motherboard in non AHCI (Legacy mode)

And here are the results after plugging the SATA III Marvel based card into the PCIe x2 slot – using one of the SATA 3 6Gb/s connectors on the card.

SATA III SSD running from SATA III card   
SATA III SSD connected to SATA III PCI-e card

Here you can see a much better score connected to the SATA III card.

I ran through Les Tokar’s (The SSD Guy) on thessdreview.com
Here’s the result after this:

SATA III SSD on SATA III Card Post Tweak

SATA III SSD connected to SATA III PCI-e card Post TheSSDReview.com tweaks

While writing another piece for the http://www.futurestorage.co.uk website I found Microsoft’s Reg tweak for Windows 7 to apply before you make the change in the BIOS at http://support.microsoft.com/kb/922976
I tried it – lump in throat – dreading the rebuild that I assumed would happen if it went wrong (I didn’t really backup either – I wouldn’t have lost a lot – but would be mildly irritating). All worked fine! I was surprised.

I did an AS SSD benchmark test before and after as well. So this test is after 1 week’s use on the drive with it on the PCI SATA III Card (AHCI enabled – on the card), but the motherboard in the incorrect legacy mode.

SATA III Pre AHCI Change
SATA III SSD connected to SATA III PCI-e card after 1 week use

So after 1 week’s use (turned on every day and used for 8 hours at least), the figure has dropped a little – this is expected – SSD out of the box will always be quicker than after is has been used for a little.

Here’s the big surprise. Here’s the stats after I made the change (ran the Registry change from Microsoft, changed to RAID On in the BIOS).

SATA III SSD on SATA II Motherboard in RAID Mode  
SATA III SSD connected to SATA II port on Motherboard in AHCI Mode

Oh boy! what a difference. I’m quite surprised. So the card has gone back in the box – the conclusion has changed drastically and in my case you are much better off just running it off the motherboard.

Looking through the web on this – the Marvel based SATA III cards have not got a good review – clearly introduce some latency.

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