Ultra Fit USB 3.0: Excessive Heat

@electronicsguy: As mentioned earlier, the temperature was measured with Infrared Thermometer which has 1.5’C accuracy tolerance.

“well one person doesn’t mean anything.” This statement also includes yourself Electronicsguy. Obviously there are lots of people that have Ultra Fits that are not functioning properly. I don’t have a digital thermometer to measure mine but as I stated when writing or formatting I can only touch it for 2 sec so it must be at least around 70 deg. Also the write speeds fall below 23MB/s so this is not functioning properly and is defective. These all should be recalled if they are running above 45c. No wonder Sandisk drives are some of the cheapest drives on the market. The only flash cards & drives that I have ever had fail/problems with are Sandisk. Anything Lexar I have ever got have been flawless and I will to continue buy Lexar instead of Sandisk.

yes ofcourse it does. but if there was a design fault, it would have been recalled. people are only complaining because its get much hotter than bigger (normal sized) usb drives. speeds fall and vary even with normal usb drives. that’s not a fault by itself.

Yes because manufactures are ALWAYS forthcoming when it comes to product recalls no matter how much money it cost them :smileyvery-happy:. How about VW diesel cars of today? If manufactures can get away by ignoring the problem and hope a government agency doesn’t find them out they will.

Yes and the only people who write on forums are ones with a complaint. the others don’t write. Is there any specific problem you have with the ultrafit other than heat or varying speeds?

@electronicsguy: I believe it is not true that only people who write in forum are the ones with complaint. Many others out there may have similar problem but there are many reasons why they do not write in forum, such as:

  1. They feel their problem has been well represented by other posters, hence once there is solution from manufacturer, their faulty device will entitle for the solution too. Why post so many posts while they indeed the same subject?

  2. They may not aware of where to complaint about their problem.

  3. They would rather let go the $$$ rather than spend time to complaint.

  4. They may not aware of the risks of the excessive heat generated by the device.

  5. They may not aware of their rights as a customer, especially those in countries where customer rights protection is weak.


Write speeds do not exceed 23MB/s,:confounded: have tested using 2 different softwares. Any USB3.0 Lexar is capable of that. I’m just keeping this drive as a backup copy of my Lexar and keep on my keychain, that way I’m not really using it. In future I’ll stick to Lexar or Patriot flash drives.

@sweetsks wrote:

Write speeds do not exceed 23MB/s,:confounded: have tested using 2 different softwares. Any USB3.0 Lexar is capable of that. I’m just keeping this drive as a backup copy of my Lexar and keep on my keychain, that way I’m not really using it. In future I’ll stick to Lexar or Patriot flash drives.

I’m afraid your argument doesn’t hold water. Look at the specs from the manufacturers and compare apples to apples. Lets take the Lexar small profile USB 3.0 as you claim. This is the official page: lexar

You can clearly see: 

16GB in orange (up to 150MB/s read, 20MB/s write)
32GB in blue (up to 150MB/s read, 30MB/s write)
64GB in teal (up to 150MB/s read, 45MB/s write)

So what exactly are you complaining about when you’re getting 23M/s write speeds? (Also remember the 23MB/s you measured is real world speed and the speeds quoted above ar “ideal” speeds which are not necessarily achieved)

Now if you compare this speed to lets say the large profile lexar one (like jumpdrive p20) which has write speeds of 80MB/s or more, then it’s not a correct comparison since that one is a large profile (hence more heat loss, so can be run at higher speeds, more channels on board, etc). But I don’t see what exactly you’re tearing your hair about for a small profile USB drive with similar speeds as the competitor.

@electronicsguy: wouldn’t it be more suitable to compare with Lexar S45 (http://www.lexar.com/jumpdrives45?category=207)) instead of S73 which is of bigger profile?

ok. compare with that. similar speeds (all theoretical there, practical will be lower. in any case range is from 20-45 MB/s)

Can anyone verify for me if there is any potential for this drive to damage USB ports?

We purchased (6) 64 gb drives to transfer data from our inspection trucks to our office computer daily.  The amount of data varies from 500 mb to 20 gb daily per drive.  The data is mostly wmv, jpeg, pdf, and mdb files.

We noticed immediately the heat issue and weren’t initially concerned, because who really cares if it just gets hot.  However, we did become concerned when nearly every USB port these drives have been plugged into have failed.  

The computers are all relatively new, I7 @ 4.0 ghz, 16gb Ram, 64 bit Windows 7.

The USB ports have failed to the point that the computer doesn’t even recognize when something is plugged in, it dings, but nothing else happens.  

If I plug one of these Ultra Fits into a working USB port, a message appears telling me that this drive has issues and must be scanned (which always results in nothing).

Can anyone tell me what the hell is wrong with these things?  Do I need to throw them in the trash where they belong?  Or will Sandisk replace them with units that don’t suck?  

To be honest, I’m leaning towards trashing them, I have had more customers complain about the reports we deliver on Sandisk drives than any other brand…

Or will Sandisk replace them with units that don’t suck?  

That’s the plan.


@kjh I guess everyone’s experience is different. I can say that I’ve used the ultrafit on my laptop and raspberry pi (continuous use) without any problems. Yes it does get hot, but its within design specs. The USB ports should not have been damaged by this heat. Of course if you could prove that the heat is outside typical USB design specs, then you would have a case.

I don’t see why Sandisk has to replace them since they dont “suck” in the first place. They’re tiny so they’re hot, get over it.

So you admit that these things suck…  Why would I want a direct replacement?  This Removed  is going in the trash.  

Btw, I am surprised at the level of Removed  you Sandisk representatives have.  

Please take some time to read our forum rules and guidelines. Foul language and personal attacks will not be tolerated. This will be your one and only warning. If you continue with the insulting posts you will be banned from posting in this community. 

Forum Admin 


1.) No one replying in this thread is a SanDisk employee or representative; only users like (or maybe not) yourself.

2.) I can’t see where anyone replying has admitted that these drives are categorically defective.

3.) There really is no need for the vulgarity in your reply.

You guys have thousands of posts on a forum for flash drives and don’t actually work for Sandisk?  

@kjh… if you can’t speak in a civilized fashion, it’s best that you don’t. No-one here is a sandisk employee. And there is no fndamental problem with the drives. If you have an issue, write a letter to sandisk rather than ranting here about non-existant problems please. Let’s move on.

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Hi guys, recently purchased the 16GB version of the Ultra Fit.

The reason this device is overheating is due to power draw via the USB 3.0 interface. I ran CrystalDiskMark with this drive sitting on a USB 3.0 port, and then a 2.0 port (both connected to motherboard on laptop).

When hooked up to USB 3.0 the Ultra Fit got ridiculously hot, to the point at which it felt like the end of a hot glue gun. When connected to USB 2.0 it was STILL HOT but tolerable.

Scores for USB 3.0:

Sequential Read  125.685 MB/s
Sequential Write 34.706 MB/s
Random Read 4KiB  : 5.780 MB/s
Random Write 4KiB  : 1.553 MB/s

Scores for USB 2.0:

Sequential Read : 41.072 MB/s
Sequential Write  : 25.743 MB/s
Random Read 4KiB : 5.357 MB/s
Random Write 4KiB  : 1.712 MB/s

According to the scores it appears that on USB 2 the drive takes a massive hit on Reading, but Writing and 4K R/W is actually fairly similar. THIS IS DUE TO THE POWER DRAW. 

Therefore, I would use USB 2.0 if transferring large files- the transfer rate will be slower but heat will be tolerable. For small files transferring via USB 3.0 would be far quicker, though less safe.

Its a brutal shame that SanDisk markets a drive for USB 3 that can pretty much be only be safely used with USB 2.0. SanDisk needs to find a balance between the two.

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So SanDisk quietly updated the models with what appears to be a small incredmental upgrade, but no changes to the physical body. Any idea if this is to address the heat issue?

I have severl 128gb UltraFit models and I generally have to use them at USB 2 speeds. I’ve always been under the impression that SD cards can function just fine with extreme heat, but USB flash drives do not have nearly as much thermal resistance due to differences in the controller.

From a design perspective, SanDisk should have used aluminum…this would make a huge difference in regards to internal temperature.

@> ZapNZs wrote:

> So SanDisk quietly updated the models with what appears to be a small incredmental upgrade, but no changes to the

> physical body. Any idea if this is to address the heat issue?


Guess not - I just got in a 128GB 150MBPS one and it overheated and did the repeated disconnect/reconnect thing when I tried to copy a folder of several GB to it :frowning: . I moved it to a USB2.0 port and so far it’s only running stoopid hot but not flaking out. I only need it to hold some .wav files to play on my .wav only device and will rarely write to it so I can live with that. Definitly not usable on a USB3.0 port! I need the low profile so I can leave it inserted in my device - a “standard” sized one wouldn’t work for me. I also have a 32GB one I bought a couple months back - I didn’t notice any problem with that one.