Question What is the difference between an SSD, an M.2 SSD, and a PCI-E SSD?

Nov 12, 2019
I am looking to buy a new computer for about £750. I'm basing it off this PC from CyberPowerSystem. There is a 1TB Seagate BarraCuda SATA-III 6.0Gb/s 7200RPM hard drive, which seems to be ok for my needs (I might upgrade to 2TB, though). As for the SSD, the current selection is a 240GB ADATA Ultimate SU630 2.5" SSD, with 520MB/s read and 450MB/s write speeds.

But there are also options for an M.2 SSD, a 2nd M.2 SSD and a PCI-E SSD. Are these just extra SSDs for my computer to use? I can get a 250GB Kingston A2000 M.2 NVMe PCIe SSD with 2200MB/s read & 1000MB/s write speeds for just £37, which seems like a decent deal. I can also get another one of the same as my 2nd M.2 SSD. All the PCI-E SSDs seem to be well out of my price range, so I'll probably avoid those.

So, what exactly is the difference between an SSD and an M.2 SSD? After a little bit of Googling, I've found out that the M.2 is primarily used as the boot drive (I may be wrong on this), so does this mean that if I get one, it will have all the Windows files on it, making it load up faster when turning on or loading files? And then the regular SSD can be used to just store games and applications that I use regularly, leaving the HDD for bulk storage? Or can I store some applications on the faster M.2 drive?

So, any suggestions for SSDs or just any advice relating to the different types of data storage would be greatly appreciated.


An SSD is a solid state drive. It can come in many form factors but the most popular traditionally has been a 2.5" SATA form factor that connects much as any other drive.

An M.2 drive can be mSATA, SATA or PCI, and is inserted into an M.2 socket. Typically, most users NOW are referring to a PCIe NVME M.2 drive when they SAY M.2.

A "PCI-E" SSD is a drive that is housed in a form factor that looks somewhat similar to a graphics card and is installed IN one of the PCI slots.

If the system is for gaming then there is little benefit to an NVME SSD over a standard SATA SSD in terms of gaming performance but if the prices are the same or similar there is little reason to NOT get one with an NVME PCIe M.2 drive because in some situations they are much faster. Gaming, and FPS, simply isn't one of those situations.

Reactions: brokeBuilder2019


I don't agree that it's "ludicrous". Not by any stretch. If the price is the same, then yes, it's silly, except in a few situations, however if it is primarily a gaming machine and you can save 20 bucks going with a standard 2.5" SATA SSD, AND that 20 bucks means the difference between a good PSU and mediocre one, then it makes a lot of sense to go without the M.2 drive ESPECIALLY since it's not like one can't be added later without losing anything and in fact GAINING an additional drive, meaning one one SSD can be DEDICATED to gaming files which is a boon.
PCIe 3.0 NVMe top off at around 3500MBps Read / Write (PCIe 4.0 NVMe is faster still)
M2. SSD and SATA SSD stop around 550MBps Read / Write

Standard 7200RPM HDD is around 155-180MBps Read / Write

Both the M2. SSD, SATA SSD and to a greater extend NVMe drives all have excellent latency and Random Read / Write especially compared to the much slower HDD's.
  1. SSD is a solid state drive.
  2. M.2 is a size format, about the size and shape of a stick of gum. a m.2 ssd can be either sata or pcie based. It usually fits into a slot on the motherboard, Possibly in a pcie adapter card.
  3. NVME is a storage protocol. One advantage of which is a more efficient instruction path designed to benefit SSD devices. Today, I know of no sata devices using nvme protocol, but I think that would be possible.
What you see today are nvme devices using the faster pcie adapters.

In general, a sata based ssd will transfer sequential data about 5x faster than a good HDD.
It will do random I/O about 50x faster. Small randon I/O is what windows does most.
A pcie device will have about the sams random i/o capabilities as sata. The sequential performance is some 5x faster. pcie is always better, but such a device will cost more than sata.

My suggestion would be to buy a 1tb intel 660P m.2 pcie device.

They are relatively cheap, About 100# and defer on the hard drive.

And... you might want to look into cyperpower, they do not have a good following on these forums.