Sammy 840 Pro Vs. 840 Evo?

S

Sharpe

Weaksauce
Joined
Jul 6, 2004
Messages
82
Greetings!

I've had a Samsung 840 Pro since they first hit the virtual shelves and love it. It was my first SSD.

However, I like what I read about the 840 Evo, which seems strange since the 840 Pro is more expensive.

I'm not concerned with differences in longevity. All SSD's will perform a long enough tour of duty to satisfy me.

I just want speed. Speed opening applications and directories with hundreds of files, both large (2 GB) and small. Speed booting up. Speed copying files from one directory to another, or copying whole directories. Speed doing anything that storage devices do. I want it to be fast. Really fast.

In plain, simple English, what are the practical, real-world differences between the two? Next to none?

Thanks for reading and for your time.
 
Pro uses faster, more durable, and more expensive flash memory
Pro has a longer warranty
I suspect the controller is better, but I don't really know.
 
If you want to maximize performance and don't care about cost, get an 840 pro.

If you want to maximize performance per cost, get an 840 evo.

Kinda like deciding between a 770 and 780 (if you follow video cards).
 
The controller of the 840 EVO is the newer one and a bit better. But it has also more to do due to TurboWrite. The 840 Pro is the better drive for IO intensive workloads, provided that it is overprovisioned enogh. The 840 EVO has a better space per cost ratio and none of the weaknesses of the original 840.
 
The 840 Evo is basically the replacement for the old 840 non-pro, uses their newest controller, and has some neat tricks like the SLC nand buffer that masks the shortcomings of the drive's TLC in normal workloads. The 840 pro uses a faster and more expensive MLC flash but hasn't yet been updated with the Evo's controller. The pro should be more durable and better able to maintain its speed on very heavy workloads that saturate the Evos SLC buffer.

edit: The SLC buffer on the Evo is 3 gigabytes, with what you're describing it sounds like you'd do better with the 840 Pro unless cost is a bigger factor than heavy workload performance. The evo "should' be faster on tasks that don't fill that buffer but the Pro should maintain performance better if you're doing lots of big sequential transfers.
 
Samsung is in business to make money. My guess is we'll be seeing a 'Pro replacement' soon. It'll have RAPID support, it'll have the better Pro NAND, new controller etc. They're all going to milk SATA 6G while they can. We're just about done on SATA 6G. It has pretty much fully matured. SATA Express 12G will be the next major 2x jump. Samsung knows this, which is one reason why they've resorted to memory caching tricks to eak out more performance. Every new SSD gen hits the wall of it's current respective interface almost immediately. From that point, everything else is fine-tuning / maturing. But the performance is 85%/90% there.
 
You won't be able to tell the difference between the two honestly.
 
Brahmzy said:
Every new SSD gen hits the wall of it's current respective interface almost immediately. From that point, everything else is fine-tuning / maturing. But the performance is 85%/90% there.
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Maybe if you only look at sequential-read numbers. :rolleyes:

SATA 3 has a theoretical max bandwidth of 6 Gigabit (750 MB/s), most SSD's can't even hit that speed when doing sequential reads, let alone small reads (4k reads are about 40 MB/s on a Samsung 840 Pro 512GB drive). And writes are even slower, for the most part.

We have plenty of room before we're done with SATA 3. When a drive manages to do more than 100 MB/s 4k reads I'll start to worry about needing a replacement ;)
 
Unknown-One said:
SATA 3 has a theoretical max bandwidth of 6 Gigabit (750 MB/s)
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Incorrect. The number is 600MB/s. The transmission line data rate is 6Gbps, but SATA 6Gbps uses 8b/10b encoding, which makes the encoded throughput 80% of the raw throughput.

That is not to say that there is no room for SATA 6Gbps SSDs to improve. They can still only do about 40MB/s for QD1 4K random read, and well under 200MB/s for QD1 4K random write. Also, sustained write speed on a full SSD is still far below the interface max of 600MB/s, especially on the smaller capacity SSDs.
 
JoeComp said:
Incorrect.
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Nope, correct as I stated it. I said theoretical max, not practical max. ;)

Theoretical max is 6 Gigabit, just like it says on the tin. Seen SATA (1.5 Gigabit) and SATA 2 (3 gigabit) speeds stated exactly the same way as above for over a decade.

JoeComp said:
That is not to say that there is no room for SATA 6Gbps SSDs to improve. They can still only do about 40MB/s for QD1 4K random read, and well under 200MB/s for QD1 4K random write. Also, sustained write speed on a full SSD is still far below the interface max of 600MB/s, especially on the smaller capacity SSDs.
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Would be interesting to see what a drive more like the 840 Pro could do with, say, an 8 GB SLC buffer. Might get performance up quite a bit for normal desktop workloads.

Might also pay to allow sequential reads/write to fall through the cache (going directly to the disk, as they would one current drives), but deffer small reads/write to the SLC cache.
 
Unknown-One said:
Nope, correct as I stated it. I said theoretical max, not practical max. ;)

Theoretical max is 6 Gigabit, just like it says on the tin.
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Wrong again. Theoretically, the maximum throughput of a SATA 6Gbps device is 600MB/s. The 8b/10b encoding is built-in to the standard -- there is no way to disable it.

Practically, the maximum throughput appears to be around 550MB/s with the overhead of the best implementations.
 
JoeComp said:
Wrong again. Theoretically, the maximum throughput of a SATA 6Gbps device is 600MB/s.
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Nope. Theoretically, the maximum throughput of SATA 3 is 750 MB/s.

Just because some of it is wasted on encoding (surrounding the data you actually want) does not change the fact that 750 MB worth of data is traveling down the wire every second (even if some of it is usable only to the bus controllers).
 
Unknown-One said:
Nope. Theoretically, the maximum throughput of SATA 3 is 750 MB/s.
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You are wrong for the third time. Three strikes and you are out!

The maximum possible throughput for a SATA 6Gbps device is 600MB/s. That is defined by the SATA 6Gbps standard. The transmission line data rate is 6Gbps, but that is not the throughput of a device as defined by the SATA 6Gbps standard. Besides, nobody cares what the transmission line data rate is -- it is irrelevant to anyone who is not implementing SATA 6Gbps transceivers.
 
JoeComp said:
You are wrong for the third time. Three strikes and you are out!
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Nope, you are. 6 gbps = 750 MB/s. That makes the theoretical max throughput of SATA 3... wait for it... 750 MB/s.

You can say "600" till you're blue in the face, you'll still be wrong. 6,291,456,000 bits (750 MB) travel down that wire every second weather you like it or not.

You're talking about effective rates, but that STILL doesn't change the fact that 6,291,456,000 bits traverse the SATA cable every second ;)
 
I wonder how much Samsungs reluctantcy to allow Magician RAPID on Pro is to boost EVO sales (probably more profit per).

Also, sure 6Gbps = 768MB/s but after 8b/10b encoding you're left with a little over 600MB/s max (614)

Unknown-One - It's not that you're wrong, because you're not, but the SATA standards are now expressed in terms of maximum theoretical performance after 8b/10b takes place. So to use the numbers you're using only confuses the issue. Everyone else uses 600MB/s to describe it because that's how the Sata industry standard describes it.
 
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Unknown-One said:
RAPID seems more like a hack to prop up the EVO's weak performance, than anything else...
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EVO's performance without RAPID is still close to Pro, you just have lower quality NAND.

Even then, I wouldn't be worried about using TLC. Hardware.info stressed 840 TLC NAND and had over 3,000 write cycles before it failed and 840 TB of written data (ironic). In three years I've wrote a little over 3TB of data to my SSD. So yeah, I'm not afraid of TLC nand in the least bit.

Now, I do redirect my Desktop, Documents, Music, Photos, and Videos to a hard drive. That does save a ton of wear off my SSD, plus saves space.
 
bigdogchris said:
Also, sure 6Gbps = 768MB/s but after 8b/10b encoding you're left with a little over 600MB/s max (614)
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No, your math is off. 6Gbps = 6,000,000,000 bits per second = 6,000,000,000 / 8 Bytes per second = 750,000,000 Bytes per second = 750MB/s

750MB/s x 8/10 = 600MB/s

Maybe you are getting Gib and Gb confused. When talking bit rates, Gbps always means 10^9, never 1024^3
 
JoeComp said:
No, your math is off. 6Gbps = 6,000,000,000 bits per second = 6,000,000,000 / 8 Bytes per second = 750,000,000 Bytes per second = 750MB/s

750MB/s x 8/10 = 600MB/s

Maybe you are getting Gib and Gb confused. When talking bit rates, Gbps always means 10^9, never 1024^3
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Yep exactly, decimal to binary. Sorry about that. 6GiBs = 750 MBps
 
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Currently the 840 Pro 512Gb offers MLC longevity, an extra 12Gb and roughly 10% more random reads for roughly £70 more than the 840 EVO 500Gb. Unless longevity makes a difference it's not really worth it.

The Pro could be quite tempting if the prices of the non-pro 840 and EVO keep rising here.
 
I really don't think it matters between EVO n PRO, we are to see Sata Express in less than two years, probably in Skylake, that will make trivial our ssds of today, even the EVO should last that long, even though there were extensive tests to the SLC nad of the 840s and was tons of decades..... personally i would recommend just get the cheapest n reliable ssd you can find, the average user wont be able to tell the difference between ssds.
 
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