Once again, we turn to Iometer to measure the most basic performance parameters.
Fantastic sequential read and write performance is a trademark of modern SSDs. To measure it, we use incompressible data over a 16 GB LBA space and then test at queue depths from one to 16. We're reporting these numbers in binary (where 1 KB equals 1024) instead of decimal (where 1 KB is 1000 bytes). When necessary, we're also limiting the scale of the chart to help readability.
128 KB Sequential Read Scaling
Just about every newer SSD ends up beyond the 500 MB/s mark with eight or 16 outstanding commands. The most notable differences come into play at lower queue depths, particularly when the queue depth is one or two.

The SanDisk drives peak past two outstanding commands, laying down a fierce 530+ MB/s. They best the next-fastest repositories, though not by much. Even at a queue depth of one, the Extreme IIs push 500 MB/s.
128 KB Sequential Write Scaling

Again, the SanDisk trio shows up swinging. The 240 and 480 GB models both touch 500 MB/s on writes, while the 120 GB version makes a splash by achieving 316 MB/s. That's actually the upper range for a 120 GB SSD, unless you're taking about a SandForce-based drive working on zero-fill data, and the most junior Extreme is on par with Intel's SSD 510 and 335 with two times the capacity.
Performance Versus Capacity
There aren't many surprises to see when we look at capacity across the LBA range. In truth, this chart should be a flat line across the entire drive. In reality, not every SSD behaves that way.
And that's exactly what we see. The Extreme IIs are seemingly wedded together, separated by just a few MB/s.

A similar story is told when we look at writes (that is to say, not a very interesting one). The larger two models are almost as quick as each other, while the 120 GB version kisses 320 MB/s. It's possible that the comparatively jagged performance line is a result of nCache.
- Extreme II, The Sequel From SanDisk
- A Guided Tour Of SanDisk's Extreme II
- Test Setup And Benchmarks
- Results: Sequential Performance
- Results: Random Performance
- Results: Tom's Storage Bench
- Results: PCMark Vantage And PCMark 7
- Results: Power Consumption
- Not Extreme To The Second Power, But Close Enough

Also, you appear to have put one of the labels back on the wrong way round.
http://www.tomshardware.com/reviews/vertex-450-256gb-review,3517.html
See here: http://www.anandtech.com/show/7006/sandisk-extreme-ii-review-480gb
It's Anand's new favorite SSD, and based on the results, I'm inclined to agree.
It's peak performance is right up there with the 840 Pro, but what's really extreme is the drive's consistency. It's performance when the drive is close to full is unmatched.
There are no high peaks accompanied by low valleys in performance when it comes to the Extreme II. It's pretty much smooth and fast sailing all the time, which in my book, places the Extreme II a step above the 840 Pro. The 840 Pro would have to be at least $30 cheaper than the Extreme II for me to even consider it over the Extreme II.
The "Heavy hitters" for modern SSDs include the fastest SSDs on the market right now, which are The Plextor M5 pro Xtreme, the OCZ Vector and Samsung 840 pro. Of these, you have only included the OCZ, and the slower version of the Plextor. Also, you have also included the old Crucial m4, which is a good drive, but old, and not one of the heavyweights now. At least include the improved "M500" version. I also find it confusing why you include the older Samsung 830.
These are minor points though. Thank you for the great comparison. I look forward to more storage comparisons
that single omission itself made this review critically flawed.
Thanks,
Chris
What we are seeing is stagnation. We have a great Marvell controller, Indilinx Barefoot 2 controllwer and a solide Sandforce 2000 series controllered SSDs.
I'm waiting for the next generation, maybe for the Sandforce/LSI 3000 series controllers that can do 200,000 IOPS! Google it. Though that drive was using a PCIe 4x interface rather than SATA but it was in the 2.5" drive form factor.
Maybe increase queue depth of 1 4KB random reads and write speeds too. So far I've only seen as high as about 30MB/s 4K random read with a queue depth of 1 on Crystaldisk Mark.