To USB or Not to USB


USB 3.0 in PC Chipsets–4 Ports, Fastest SSDs

Some leaked slides on a Chinese website showing a PC Chipset with 10 USB 2.0 ports and 4 USB 3.0 ports.   Now you might ask, why only 4 USB 3.0 ports?

Isn’t USB 3.0 is faster than USB 2.0?  Yes

Isn’t USB 3.0 more power efficient per GB of data transferred?  Yes

Doesn’t USB 3.0 got to sleep faster and wake up faster for better power savings?  Yes. 


Last Week’s Question of the Week

What is the maximum theoretical read/write speed of a SATA 6 Gbps equipped SSD?
What is the fastest claimed speed?
What is the fastest benchmarked speed?


Mr. Posner wrote in:

What is the maximum theoretical read/write speed of a SATA 6 Gbps equipped SSD?

600 MB/s – Source: My brain, 6 Gb/s signaling with 8b/10b encoding

What is the fastest claimed speed?

Read 550 MB/s / write 525 MB/s – Source:

What is the fastest benchmarked speed?
Read 550 MB/s / write 520 MB/s -Source: is the ATTO test which reports raw performance)

So the maximum theoretical speed should be 80% of 6 Gbps or 4.8 Gbps.
This assumes zero latencies in the 1) PC, 2) Drive, 3) Drivers, 4) OS, 5) Peripheral firmware…

At a measured read speed of 550MBytes per second this equals about 4.4Gbps.  Reading through the Tweaktown article, the fastest previous SSD  reads at 285 MBytes per second.

So the fastest memory and the fastest SSD today, in 2011, can start to take advantage of USB 3.0.  Only SSDs of the highest speed get the full throughput 10x throughput.  More importantly, mainstream SSDs (or HDDs) can still take advantage of USB 3.0 at 3x-8x USB 2.0 speeds.  As the price of the high-end SSDs come down, USB 3.0 becomes more useful.

Why ask this question now?  Doesn’t this argue against USB 3.0?

The real reason to ask is Thunderbolt.  Even if Thunderbolt can delivered sustained 10 Gbps (which probably is 8b10b encoded, so less now) then the peripherals that serve data up at 10Gbps will cost 50% or more of the cost of a laptop.  So Thunder (for now) is directed at a fairly narrow market.

USB 3.0 – Immediately useful today, Tomorrow more useful.


Today’s Question of the Week

Why would I put faster flash memory (like the SSD above) in my Smart Phone?

Will PC’s go away?

Answer in the comments below.


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