We're dealing with the same chassis as the original 840. It's far better than the old 830 when it comes to accessing the internals, but you do need pentalobe drivers to remove three screws. Do I even need to mention that doing this defaces the pristine label and voids your warranty? Probably not.
Also like the 840 EVO, PCB size depends on capacity. Of the three models I'm testing, none fill the entire enclosure. Instead, we see this:

The 1024 GB drive (left) employs a slightly longer board, with four packages on the front and four on the back. The 128 GB version (right) gets just four packages total.
Here's a close-up:
1024 GB 850 Pro PCB
Isn't that MEX controller pretty? It wears 1 GiB worth of LPDDR2 like a funny hat in this 1024 GB implementation. Samsung's Pro family includes 1 MB of cache per GB of capacity, so the 128 and 256 GB drives come with 128 and 256 MB worth of DRAM.
The NAND part numbers aren't decipherable without an updated decoder. For now, I can tell you that the packages you see on-board all come from Samsung. I'm making an effort to dig up additional details, but it'll probably take a trip to South Korea for answers. Of course, if you're reading this on launch day, that's exactly where I'll be, too.
- 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.