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Gen5 SSD vs Gen4 SSD - What's the Difference?

PCIe Gen5 is knocking on the door, with the first drives already hitting the market with some impressive read/write speed claims. Join us as we take a closer look at how Gen5 SSDs compare to Gen4, and whether it's worth investing in an upgrade.




Since solid state drives (SSDs) first hit the market and relegated traditional home PC hard-drives to back-up and media storage duties, SSDs have themselves undergone significant changes, improvements and had an outright connectivity revolution, with the fastest drives moving from a SATA cabled connection, to plugging directly into motherboards via M.2 PCIe slots - improving read and write speeds dramatically.

Since then we've seen steady improvements in the technology, with each generation of the PCIe standard marking a doubling of the theoretical max speed.


Intel PCIe Speed Chart


This chart, *courtesy of Intel*, should give you an idea of the fundamental throughput each generation of technology is capable of - this is the raw bitrate of the tech, and is applicable across any components that utilise a PCIe connection on your motherboard, such as your graphics card - this is also the speed *per lane* - with different PCIe connections occupying different numbers of lanes.

Your massive chonker of a graphics card will use a PCIe x16 slot - the x16 indicating that the slot uses 16 lanes. More lanes means more bandwidth, something every modern GPU needs plenty of. Your M.2 NVMe SSD on the other hand will use a comparably modest 4 lanes, and the upshot you can anticipate when migrating up the generations will be benchmarked in MB/s and not GT/s.

So what IS the upshot?

PCIe gen3 probably doesn't seem particularly old to many of us, but it's been around since 2010, in what has been a remarkably eventful 13 years for both technology and the world in general. Back then our data was cruising along at a leisurely maximum of 3940MB/s, and it was 9 whole years before Gigabyte teased the World's first Gen4 SSD - that drive was touted as capable of reaching 5000MB/s, and this speed would be improved on over time, with Gen4 capable of a theoretical 7880MB/s.

On a graph that looks... just like the previous graph, obviously, but now we have the theoretical MB/s as a metric for some closer context to our use-case of SSDs, rather than PCIe as a whole.


Intel PCIe Speed Chart


These theoretical speeds are never really reached, but hardware tends to get close - as an example for Gen3 Samsung's 970 EVO Plus SSD reached 3500/3300 MB/s Read/Write speeds, while their Gen4 990 PRO reached 7450/6900 MB/s. The theoretical top-speed for Gen5 should be 15800MB/s, and the first drives to market are already over the 10000MB/s mark, with LinusTechTips benchmarking Crucial's T700 SSD at an impressive 12422/11858 MB/s sequential read/write in a CrystalDiskMark test.

Does Gen5 go that fast in practice?

Sequential read/write is the most straight-forward of speed tests and gives us an idea of how the drive performs when it can stretch its legs and sprint. Most of the work you'll be doing on a PC however doesn't really lend itself to sprinting - there are too many obstacles, twists and turns in the reality of navigating your storage (especially yours. Yes, you!).

That means that in practice for the average gamer the speed benefits you'll experience with Gen5 over Gen4 aren't as significant as they are on paper, as in daily use you won't regularly see that blistering speed shine - if anything, these Gen5 SSDs are overtuned for their workload - the speed is there, but unless you spend a lot of time moving files around you won't necessarily get the most out of it.

Is a Gen5 SSD worth it?

The question at the heart of the affair is whether it's worth dropping what you're doing and running off to purchase the speediest of storage post-haste. The answer really lies in why you'd be doing that - if you're an early adopter who loves having the latest and greatest then obviously the answer is always yes, do it now, sell the dog if needs be (Disclaimer: DO NOT actually sell the dog).

Otherwise you'll need some solid, well thought out rationale for the upgrade - and as usual when it comes to new gaming tech, that rationale will rear its head in the form of future-proofing.

if you're planning to overhaul or replace your system anyway, then it makes sense to at least consider the implication of the change in technology, even if you don't buy a Gen5 SSD immediately. If you want a system that's reasonably future-proof your new motherboard will need to support PCIe Gen5 anyway, which in turn means a gen5 SSD may bear some consideration when filling your basket with shiny components, depending on your budget and aforementioned proclivity towards the latest & greatest tech.

Another consideration is DirectStorage, which while hardly prevalent at the moment, is likely to start seeing some traction in games as developers get to grips with using, and making the most of the technology. This again is a case for future-proofing, rather than for adopting Gen5 with any urgency, but the potential is there.

So what's the fuss about?

If our concern with Gen5 is that we're going to have trouble realising its top speeds in practical use, then perhaps we're looking at this particular advancement the wrong way. If Gen4 speeds are already fast enough that we're not seeing noticeable improvement, then perhaps we don't actually need to use 4 PCIe Gen5 lanes for an SSD anymore, as with Gen5 we can get Gen4 speeds out of just 2 lanes, which frees up the other 2 lanes to be used for something else - like... another SSD!

Perhaps the benefits of PCIe Gen5 will eventually manifest in a lane revolution, with Gen5 motherboards reconfigured to allow more connections, rather than faster ones - once again, the potential is there.

PCIe Gen5 could be very exciting - just perhaps not exactly in the way we might have expected.

TLDR: What is the difference between PCIe Gen4 and Gen5 SSDs?

SSDs with Gen5 are theoretically capable of double the speed of Gen4, with drives already hitting the market at sequential read/write speeds in the 10-12MB/s range. These speeds are hard to put into practice in daily use, however, and until we see DirectStorage in more common use it's hard to say whether that'll be a serious consideration for gaming. The potential for Gen5 is compelling though, and if you want your next system to be future-proof you'll at least want to make sure your new motherboard has Gen5 support.