6 Gb/s SSD running at 3 Gb/s only

G

Gabor

Active member
I have two SSDs in my Vortex II:
120GB INTEL® 520 SERIES SSD, SATA 6 Gb/s (upto 550MB/sR | 520MB/sW)
240GB INTEL® 520 SERIES SSD, SATA 6 Gb/s (upto 550MB/sR | 520MB/sW)

The first one is the primary drive and holds Windows 7, the second one is in the DVD bay and stores data.
Intel Control Centre / Intel Rapid Storage Technology application shows the first one as 6 Gb/s but the second one as 3 Gb/s only. SiSoftware Sandra Light shows the same.

Why do I not get the full speed of the second drive?
 
Buzz

Buzz

Master
It depends on your motherboard and how many Sata 6 ports it has. Usually Sata 6 GB/s are white/gray ports on most motherboards. Sata 3 Gb/s are usually a light blue color. and then Marvell would be on the Navy Blue. Just double check to make sure that the Sata cables you are using are Sata 6Gb/s (usually has printed on the cable somewhere) and make sure they are connected to the correct port on the motherboard. Also use the flat end of the sata cable for plugging into the motherbaord header and the angled end (if it is in fact an angled end) into the SSD.

Hope this helps. Without knowing your comp specs I cant say much more really. You should have a motherboard manual which will guide you further.
 
G

Gabor

Active member
My fear is that the Vostro II laptop's motherboard has only one 6Gb/s Sata port and so I can run the second drive at half speed only. Is there an online manual for the motherboard where I could check? Can Windows 7 tell me the speed of Sata ports?
 
Maestro

Maestro

Guest
Yes, the sata connection for the optical drive bay will only be 3 GB/s as I don’t believe there are currently any optical devices that use 6 GB/s yet (I could be wrong). However, you will notice only minimal performance difference if any, between the two. Benchmarks may show a difference, but your ssd will still be incredibly fast whether on a 3 GB/s or 6 GB/s controller.
 
G

Gabor

Active member
Maestro, can you explain why there will not be much difference between 3Gb/s and 6Gb/s? Strictly speaking that means half the speed.
 
Maestro

Maestro

Guest
Its not quite as clear cut but think of it this way.

Your ssd can maybe write at 550mb/s, your sata controller, even sata ii is 3gb/s.

There will definately be a slight improvement if you compare bench's between 3gb/s and 6gb/s, but maybe single digits upto a max of about 20%. And because they run so fast anyway, you will not notice any performace degradation in the real world.
 
Finn

Finn

Enthusiast
Maestro said:
Your ssd can maybe write at 550mb/s, your sata controller, even sata ii is 3gb/s.
Click to expand...

Sorry that isnt true. The quoted figure for the bus is in gigabits per second. The SSD quoted speed is in megabytes per second. Although there are normally 8 bits to a byte, there are 2 bits of overhead when transferring across the bus so to find the maximum data transfer speed you divide by 10 instead of 8. So Sata3 is capable of 600 megabytes per second, sata2 of 300 megabytes per second.

Now, whilst its true that in general usage you are unlikely to be able to see the difference, there are situations where its apparent. if your doing sustained sequential reads or writes then the speed will be approximately half what the SSD is capable of. Simply running programs/reading data is unlikely to do that though.
 
Finn

Finn

Enthusiast
Err that article finds a maximum increase of 20% for a hard drive (a WD cavier black to be precise) the only SSD they test is only capable of SATA2 speeds anyway.

I cant find an article where they actually test a modern sata3 ssd drive on a sata2 controller and measure the speed difference, but if you look at the benchmark here http://hexus.net/tech/reviews/storage/34729-intel-520-series-ssd-240gb/?page=3 you can see that for 32k read/writes and above the speeds recorded are beyond the maximum 300megabytes per second of the sata2 interface. you can effectively crop those bars to somewhere under 300 and that will show you the difference.
 
Maestro

Maestro

Guest
maybe somebody could test this for us. ATTO disk benchmark is good. If you have an ssd, test it on the 6gb controller then swap it to the 3gb controller and post the results.
 
Finn

Finn

Enthusiast
The OP should be able to test both his sata3 C: and Sata2 d: :)

Whilst not stricly apples to apples the 240 is actually quicker than the 120 so should be a reasonable comparison of what its being limited to.

Although while checking that I did find this link http://www.anandtech.com/show/5508/...cherryville-brings-reliability-to-sandforce/2

which seems to show that the 240 is 550/520 on SATA3 and 280/260 on SATA2 whilst the 120 is 550/500 on sata3 to 280/260 on sata2
 
G

Gabor

Active member
By running the benchmarks, do I want to rub it in for myself that I wasted money on performance which I cannot use? ... OK, I'll have a look at ATTO.

(I can always rationalise that I needed a 15.6" laptop with SSDs only because I may use it close to strong magnetic fields near MRI...)
 
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