Comparison of Samsung 840 & 840 Pro

Comparison of Samsung 840 & 840 Pro

Many people ask when they upgrade to an SSD if they should get a Samsung 840 or the 840 Pro and want to know the difference. I usually say that unless they are in a production/enterprise environment where they will be doing excessive writes to it daily, then they don’t need the Pro version.

Samsung Electronics Samsung 840 Series Solid State Drive (SSD) 500 GB SATAIII 2.5-Inch MZ-7TD500BW

The NAND on the non-Pro is made from TLC while the Pro version uses the more robust and durable MLC NAND. The MLC allows the Pro to have a better write speed and stands up to more writes than the non-Pro before degradation begins to occur.

If all you’re looking for is a faster boot time and faster application load times, then the non-Pro is all you need. The read speeds between them is negligible and would only be noticed in benchmark tests.

Are you worried about the non-Pro wearing out too soon? The non-Pro is designed to last at least eleven years while writing 10GiB per day with a write amplification of 3x. After eleven years, it’ll likely be obsolete along with the computer it’s in before the NAND starts to degrade.

As you can see, from the testing done at Anandtech, the read speeds are very similar even with the 830 included. The write speeds are drastically different, but as I mentioned before, unless you do a lot of heavy writing each day, one doesn’t need the Pro version.

I’m all for top-level performance, but when the prices of SSD’s are still very high compared to their much slower counterpart, the hard drive, you’re going to pay an even higher premium for the Pro version. For the average user, the Pro version is just a waste of money when they won’t be exercising its full capabilities for cost.

Here is a speed test of the Samsung 830 in my MacBook Pro, which I used to write this article. Even as a non-Pro model, it screams speed and even boots to a useable desktop in 15 seconds.

The bottom line is, if you’re on a budget and don’t intend on heavily writing to your SSD daily, then go for the non-Pro 840. However, if money is no object, then get the 840 Pro and enjoy the faster write speed.

iMac Temperature Sensor Dummy Load

iMac Temperature Sensor Dummy Load

This is an update to my other posting about the upgrade of my 2010 iMac to the Samsung 840 SSD. In that post I had an issue with controlling the HDD fan since the sensor was unable to be connected to the SSD. With the sensor disconnected the fan would run at full RPM continuously. I was able to control the speed with software on just about every event the computer would go through, such as startup, shutdown and wake from sleep. The only event I couldn’t control was wake for network access. That event occurs when I access the iTunes library from the Apple TV at which point the fan would run at full RPM again. The only way I got around that was to never put the iMac to sleep, leaving it on all the time and only putting the display to sleep.

Samsung Electronics Samsung 840 Series Solid State Drive (SSD) 500 GB SATAIII 2.5-Inch MZ-7TD500BW

I got to thinking the other day that Apple probably didn’t read the HDD temperature by sending data from the HDD itself, but rather measuring the temperature of the jumper pins on the HDD, where the sensor plugged in.


I had an old HDD which didn’t work anymore and I removed the controller board from it because it had the IDE jumper pins on it. I took that and used some 3M 2-sided tape and stuck the controller board to the SSD and connected the temperature sensor cable to the jumper pins. I didn’t connect any power or anything else.

I put the iMac back together and turned it on, removed all my software tricks and scripts and restarted again. I went though all the events of startup, shutdown, restart, wake from sleep and wake on network access and never once did the HDD fan spin uncontrollably. It worked!

The fan stays at a speed of around 1100 to 1200 RPM’s and I figure the ambient temperature inside the iMac affects the pins a little and that’s what gives the various speed readings of the HDD fan. The dummy load HDD controller board from a dead HDD did the trick. It’s too bad for me that I didn’t think of this sooner, like 2 or 3 months ago.

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