We’ve now received over 20,000 benchmarks at https://pibenchmarks.com/! These are submitted by regular people from all over the world.
In celebration of that milestone as well as the launch of the 8GB Raspberry Pi 4* take a closer look at which device you should choose for your Raspberry Pi 4 as determined by science and measurement!
Best Performing Devices
Solid State Drive (SSD)
Samsung 970 EVO Plus NVMe SSD
The Samsung 970 EVO Plus is a fantastic drive and has fallen in price substantially. It’s widely available around the world. The smaller capacities (such as the 250GB version) of this drive are perfect for the Pi! This is the top performance option without going into the “Pro” series of the lineup which are much more expensive.
The SanDisk Extreme A1-A2 SD card has the best scoring SD card on pibenchmarks.com for years and is second in popularity only to the SanDisk Ultra (often included in combo kits). The application class (A1) means random I/O speeds (very important when running an OS) have to meet a higher standard. There’s no benefit on the Pi for A2 right now so get whichever is cheaper/available.
The SanDisk Extreme A2* is barely edging out the SanDisk Extreme A1 variant* for the top spot. The difference is tiny though, so you should pick whichever one is cheaper at the moment.
Benchmarking / Testing Storage
If you want to verify your drive’s performance you may want to run my storage benchmark with:
If you search for the model of your drive on pibenchmarks.com you can compare your score with others and make sure the drive is performing correctly!
Storage Adapter Performance Note
The type of USB adapter you use (if you aren’t using a SD card) can have a big effect on performance. I cover which adapters are good and which should be avoided more comprehensively in my Raspberry Pi 4 USB Booting Post.
The benchmark only takes a few minutes and will give you a lot of information about whether your Pi is performing well or not. Storage is definitely the biggest performance variation between otherwise identical Pi setups.
Compare your score with others at the full benchmark browsing site https://pibenchmarks.com/. Leave a comment letting us know how you did or if you need any help!
Power Requirements
Most types of storage adapters can be powered by the Pi itself. One notable exception is NVMe enclosures. Throughout the years we have had hundreds of comments from people who had no trouble powering 2.5″ SATA enclosures but couldn’t get a NVMe one to work at all without a powered USB hub.
Very large older 3.5″ SATA drives are known to require more power than the Pi can provide as well as some types of very high performance models that were designed to burn more power to get extra performance gains.
For solid state storage older models of solid state drives (SSDs) are also known to draw more power than their newer counterparts. If you have a drive that you think may fall into this category then definitely be on the lookout for power related issues and extra cautious about your power setup. High end “extreme” performance models also tend to draw more power (Samsung 970 NVMe drives* are some of the fastest in the world but also pretty power hungry for the Pi).
Insufficient Power Symptoms
Symptoms of a lack of power to the drive can include the system only booting sometimes (or not at all) or working for a while and then locking up. Just because the drive boots does not mean it is getting enough power.
Some commenters on previous articles have described this as working fine until there was a sudden spike in CPU usage while they tried to do several things at once (high CPU, accessing storage, activating various hardware all at once) and then they would get a lockup/crash.
This is because the Pi is teetering on the edge of not having enough power and that spike caused it to drop enough where the drive actually lost power (likely only for tiny fractions of a second). This is enough instability to easily cause a crash and worse if it happened to be in the middle of writing something important! Usually nothing will happen other than you’ll have to restart the Pi but because of the risk of data loss and eventually corrupting files. That being said, if you’re particularly unlucky you will have to fsck the drive or potentially even reimage it if fsck is unable to repair the damage!
The best answer is to test for stability. Do this by stressing out the Pi and make sure you are doing activities that stress the CPU and storage at the same time like browsing the web, etc. and if you can do that for a few hours/days without a lockup/crash then you have a stable power setup!
Powered USB Hub Solution
For NVMe enclosures and power hungry drives I personally use this Sabrent powered USB hub and have been recommending it here on the blog for a long time:
Sabrent Powered USB 3.0 Hub
The Sabrent powered USB hub delivers a whopping 2.5A of dedicated power for your USB attached devices. This is almost as much as the Pi adapter itself is rated for (3.0A). It will easily power the most thirsty of setups such as NVMe enclosures.
Note: Make sure Amazon doesn’t try to take you to the non-powered version and that it’s the one with the AC adapter that plugs in to provide extra power
If this hub isn’t an option for you and you don’t have one already you can try with it then look in the reviews for people saying that it is working with Raspberry Pi. Some powered USB hubs will not play nice with the Pi so before buying one definitely check reviews and do some careful research about what to expect with the Raspberry Pi!
Oversized Power Adapter Solution
This solution will work for setups that are right on the border of having enough and not having enough power. An example would be if you can get a stable boot but are getting occasional lockups/freezes when the power dips just below the threshold it needs.
If you are using a powerful NVMe drive/enclosure combo like the ICY BOX with a high performance Samsung NVMe drive even with the extra 500 mA it will still not even boot. I have had these oversized adapters and they are great but for a very powerful drive/adapter combination you are going to need more than 500 mA.
It’s a lot less extra wires and one less AC plug though if you are right on the border and just need a little bit more. It will depend on your individual drive/adapter combo whether it’s enough or you will have to go full powered USB hub!
CanaKit 3.5A Power Adapter
The CanaKit 3.5A adapter has an extra half an amp (500 mA) of capacity to give some breathing room to your accessories. This is bigger than the official Pi power supply which provides 3.0A.
In previous articles readers have told me that this specific adapter can be hard to find outside of North America. I tried to link to as many regions as I could find it in but there should be something equivalent in your region (it just likely won’t be specifically designed for the Pi but will be a more generic USB-C charger).
Look for a USB-C power supply rated to supply around 3.5A. 3.0A or lower won’t do much good as that is almost certainly what you already are using. You can use a higher one (at your own risk). The largest one I’ve ever used is my Dell laptop’s 30W USB-C power adapter. It’s probably not a good idea to go too much bigger than this or to even use one this big over the long term (I didn’t, just for occasional testing and as a emergency backup) but USB-C does have some specification improvements related to power management that seem to provide some flexibility here.
Power Limits
The Pi can only pass through a limited amount of extra power. On the Pi 4 this is up to 1.2A of extra power for peripherals (combined) on top of the board’s 3.0A power rating. This is much more than the Pi 2 and some other previous models could do which was only around 0.5A. This also means that getting a power adapter bigger than about 4.2A of rated current is pointless because the Pi won’t allow any more power to flow through to the board to the peripherals through USB anyway even if it’s available.
I’m oversimplifying a little bit to illustrate the point but if you want the full technical details they are available here in the Raspberry Pi USB documentation. The important takeaway is that going much above 3.5-4.0A or so will not actually provide any more power to the Pi because of these limits. If you’ve hit this ceiling and it still isn’t enough you need to go powered USB hub.
I’ve also used ones that charge cell phones to power Pis before and these ones are the most likely to fall into a range close to what the Pi uses. Most of the ones I had around the house for phones were 2.5A (just barely not enough) or 3.0A so it was enough for a backup spare but not enough to provide extra power. Nevertheless, it’s definitely worth it to check what you already have around and see if there are USB-C chargers around to test with!
Note that a powered USB hub essentially bypasses these limits because the power for your peripherals such as your USB storage will come from the AC adapter connection to the powered USB hub instead of the Pi having to provide that power.
Powered USB Hub Troubleshooting
Most hubs including the Sabrent one above can feed back power into the Pi which can cause it to not boot when the power is connected. The reason for this is that the Pi is detecting power and is trying to power on using that source but the current provided isn’t enough for the Pi to actually boot.
The solution to this is to remove the USB hub’s connection from your Pi momentarily and then connect the power. Plug your USB hub back in quickly after reconnecting the Pi’s power (if you have native USB booting set up) and unless you really fumble with reconnecting it you will have it plugged in well before it tries to boot from the SSD!
If this trick doesn’t work then unfortunately you may have a powered USB hub that is not going to work with the Pi. It’s worth checking to see if there are any firmware updates available for your USB hub before you give up on it as some readers have let me know in the comments of previous articles that they were able to get some hubs working after a firmware upgrade!
Other Resources
If you’ve having firmware problems with your Pi such as it blinking and refusing to do anything else or know that your firmware is very old (from before native USB booting was added) check out my Raspberry Pi Bootloader Firmware Update / Restore Guide
