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 numbers (where 1 KB is 1000 bytes). When necessary, we also limit the scale of the chart to enhance readability.
128 KB Sequential Read
There's not much difference between drives in this metric. Then again, I didn't expect any. Getting 538 MiB/s is about all we'll see from SATA 6Gb/s, and these could have been any three drives to pass through my lab lately; they're all hitting the interface's ceiling. On to the writes.
128 KB Sequential Write
The 128 GB 850 Pro is the only drive to register lower performance, as we knew would be the case. But hitting 460 MB/s is no joke. No other 128 GB drive I have comes close. Note that, first, I'm using 128 KB access sizes, and second, reporting in binary, not decimal. In decimal, that'd be 482 MB/s. Put another way, the 128 GB 850 Pro pushes 100 MB/s more than the 840 Pro at 128 GB.
Samsung's 256 and 1024 GB models are blazing fast, demonstrating throughput in excess of 510 MB/s (again, in binary). That's as fast as you're going to see from a SATA 6Gb/s-based SSD.
Here's a breakdown of the maximum observed 128 KB sequential read and write performance with Iometer:
Sorted by combined maximum read and write throughput, two 850 Pros establish beachheads just below the pair of PCIe-based SSDs. No drive with a SATA interface can claim to deliver more sequential performance. And again, dig through this chart and you'll find that no competing 128 GB-class offering touches the 850 Pro.
- Samsung 850 Pro SSD: Introducing V-NAND
- Inside Of Samsung's 850 Pro
- How We Tested Samsung's 850 Pro
- Results: 128 KB Sequential Read And Write
- Results: 4 KB Random Read And Write
- Results: Tom's Hardware Storage Bench v1.0
- Results: PCMark 8's Expanded Storage Testing
- Results: TRIM Testing With DriveMaster 2012
- Testing The DevSlp Power State With Some New Gear
- Results: Power Testing
- Results: Latency And Performance Consistency
- SATA Is Maxed, But The 850 Pro Still Pushes Faster



I don't know if this really changes anything for you. Two EVOs are still going to be better than one 850 Pro in [most] every way. But I understand the sentiment!
Christopher Ryan
You just ordered a few hours ago. Just cancel your order if you really want this 850 Pro.
I can guarantee that in 10 years you won't own that drive anymore.
Can you test on an AMD platform which makes it easier to over clock that bus and some of the connected components?
I don't know if this really changes anything for you. Two EVOs are still going to be better than one 850 Pro in [most] every way. But I understand the sentiment!
Christopher Ryan
Not quite. One is for my Desktop, the other is for my Father's Desktop.
For my Desktop, I'll be stepping up from 2x OCZ Vertex 2 60GB in RAID 0. Hope it'll be worth it...
I don't know if this really changes anything for you. Two EVOs are still going to be better than one 850 Pro in [most] every way. But I understand the sentiment!
Christopher Ryan
Not quite. One is for my Desktop, the other is for my Father's Desktop.
For my Desktop, I'll be stepping up from 2x OCZ Vertex 2 60GB in RAID 0. Hope it'll be worth it...
That would be to give more room for the sidebar adverts.
But the limit has now been reached in almost every way.
Which solution will stick? Anyone care to guess?
I disagree. SATA Express melds the convenience of SATA and pcie performance. With NVMe and Gen 3 PCIe, I think there WILL be much to like.
Christopher Ryan
I'd rather start seeing IOPS crank up to RAM levels.