Four big differences between DDR3 and DDR4 RAM

Patriot Viper 4
Patriot Viper 4 (Image credit: Rich Edmonds / Windows Central)

Not having enough RAM in your PC can truly wreck your day no matter what you're trying to accomplish. If you're in the market for more RAM, you might be wondering about the differences between DDR3 and DDR4 RAM, and whether or not they really matter to you.

RAM explained

The random-access memory (RAM) in your computer is used to hold data that is frequently accessed by your processor (CPU). It can be likened to your office where you have a corkboard with a bunch of papers on it for easy, quick reference.

Why use RAM when we have hard-disk drives (HDD) and solid-state drives (SSD)? Reading from and writing to a hard drive, even a solid-state drive, is much slower than reading from and writing to RAM. The connection between the CPU and the RAM, also know as the memory bus, is designed for speed, and the entire package uses a small amount of energy to do its job. Accessing a hard drive is sort of like standing up, opening a filing cabinet, and pulling out a paper — much slower than if the paper is already on a corkboard in front of you.

DDR3 and DDR4 RAM don't work together

The first noticeable difference between the two RAM-types is the physical layout of the pins on each module. DDR3 RAM uses a 240-pin connector, while DDR4 RAM uses a 288-pin connector.

DDR4 RAM with 288 pins

Why are they different? A motherboard and CPU that work with DDR3 RAM don't work with DDR4 RAM and vice versa. The different connectors ensure no one accidentally installs the wrong type of memory. Also, take note that not all RAM works with all processors, even if it fits into the motherboard. Take time to research and make sure all parts of your PC are compatible. If you need a hand, PC Part Picker has a wonderful tool that shows you what works together and what doesn't.

You might also hear mention of DDR3L RAM. This RAM has the same pins and works with any CPU and motherboard that works with DDR3 RAM. The difference? DDR3L RAM can function at both 1.5V and 1.35V, while DDR3 RAM is stuck at 1.5V.

DDR4 RAM looks faster on paper

When studying data transfer rates of RAM, you'll see it measured in either million transfers per second (MT/s) or gigatransfers (billion) per second (GT/s). A higher transfer rate means you have more bandwidth and will thus be able to transfer more data at once. DDR4 RAM can transfer data at a rate between 2133MT/s and 4266MT/s, while DDR3 RAM can only hit transfer data rates between 800MT/s and 2133MT/s.

Another number you'll see is the clock speed, which is how fast the RAM can read and write data. The clock speed number, represented in megahertz, is the number of cycles per second the RAM can perform.

Finally, Column Access Strobe latency, also known as CL, must be taken into consideration. CL is the number of clock cycles it takes for the RAM to deliver a piece of data requested by the CPU. Even if you have blazing fast clock speeds, high latency will put a damper on your RAM party.

If we compare four types of Corsair RAM, it's evident that a higher clock speed and the higher transfer rate afforded by DDR4 RAM doesn't necessarily always make it better.

Swipe to scroll horizontally
NameTypeClock speedLatencyResult
Corsair Vengeance Pro (opens in new tab)DDR3L1600MHzCL99/1600MHz = 0.0056
Corsair Vengeance LPX (opens in new tab)DDR42400MHzCL1414/2400MHz = 0.0058
Corsair Dominator Platinum (opens in new tab)DDR32400MHzCL1111/2400MHz = 0.0045
Corsair Dominator Platinum (opens in new tab)DDR43200MHzCL1616/3200MHz = 0.0050

When shopping for RAM, always take all specifications into consideration. Higher numbers on the label don't necessarily mean faster performance.

DDR4 RAM uses a lower voltage

The standard voltage of DDR3 RAM sits at 1.5V, while DDR3L RAM can use both 1.35V and 1.5V. DDR4 RAM, on the other hand, uses 1.2V. While this isn't a big difference for most of us using one or two RAM modules — you're not going to see a difference on your electricity bill — server farms with thousands of RAM modules will definitely enjoy sucking less power.

DDR4 RAM costs more

When DDR4 was first released, the price gap was quite large. The gap has shrunk a lot since then, but in general, DDR4 RAM still costs more.

If we look at the prices of the Corsair Dominator Platinum RAM from the table above, it's clear that even though the DDR3 RAM performs better when considering clock speed versus latency, it is still cheaper — DDR3 costs about $115 (opens in new tab), while DDR4 costs about $130 (opens in new tab). Again, this isn't a huge difference if you're only buying one or two modules, but in instances where you need a lot of RAM, the cost can really add up.

So...which RAM do I choose?

Going with DDR3 or DDR4 RAM really depends on what other hardware you're currently using, and what hardware you plan on using in the future.

If you have an aging motherboard and a 4th- or 5th-generation Intel CPU, you'll probably be going the route of DDR3 once you figure out all the compatibility stuff. If you have a recent motherboard and, say, a 6th-generation Intel CPU, DDR4 RAM is a good investment for the future — it's hard to believe DDR4 RAM won't be used for quite some time to come.

Which RAM do you use?

What are you running in your PC build? Were you able to go with DDR4, or are you still using DDR3? Tell us in the comments section below!

Cale Hunt
Senior Editor, Laptop Reviews

Cale Hunt is a Senior Editor at Windows Central. He focuses mainly on laptop reviews, news, and accessory coverage. He's been reviewing laptops and accessories full time since 2016, with hundreds of reviews published for Windows Central. He is an avid PC gamer and multi-platform user, and spends most of his time either tinkering with or writing about tech.

59 Comments
  • If looking at a new system purchase, or even a new build, it may end up being DDR4 anyway given the current trend. It seems like many mobo builders are heading away from ddr3 and going solely with ddr4. Thank you, that was a good article.
  • It also seems that DDR4 (in some cases) is cheaper than DDR3 ram. Crazy world we live in :).
  • FYI - Clock is measured in MegaHertz (MHz) not millihertz. 1 MHz = 1,000,000 hertz. Millhertz = 0.001 hertz = slow as molasses, or black treacle for you folks in the UK.
  • I was shock when i read miliHertz, i haven't see any real usage for that yet.
  • Ha thanks. Fixed.
  • Ah, also measurement on clock speed is 1 clock = 1 hertz, so if it's 1600MHz, then it's 1600000 clocks per second, meaning if we find the CL (assuming a DDR3 RAM with 1600MHz and 9CL), then the time needed to respond isn't 0.005625 seconds, but 0.000005625 seconds instead.
  • Ah, was about to say that too, before... dem slow Internet connection... smh
  • What's with the names of memory brands?  Mother F'n Murder XTREME! Pro Plus Ultra...
  • Hahaha
  • but the PS4 uses a GDDR5 RAM. why not use that in laptops too?
  • GDDR and DDR are a different thing. Look up the differences to understand them.
  • G- means GRAPHIC its for the GPU not the system
  • DDR and gddr are quite different. The main difference is that gddr moves data at slower clocks in larger chunks. This makes moving large texture data fantastic, but turns out to be rather inefficient for normal computer data.
    Plus gddr is expensive... No point in putting expensive ram on the mobo when it runs like poor. Best to keep it on the gpu where it belongs. As a side note; the ps4 uses it as a way to have a unified memory architecture. Because almost everything it does is video and texture processing it made sense to have more gddr than splitting their budget between DDR and gddr. The Xbox on the other hand is just a cheap pc with a custom OS on board... So you win some, and you lose some with both ways of doing things.
  • My main gaming rig is DDR4 (16GB), but my old system I used for video editing is still on DDR3 (32GB). At work our media servers use either DDR3 or 4 depending on the requirements. For those looking to do an upgrade and save a bit of money in the process, you can find some motherboards that have slots for both. This way you can hold on to DDR3 you already have and then upgrade to DDR4 if/when it makes sense and fits your budget.
  • MHz is megahertz, not milihertz. :)
  • Whoops - thanks. Fixed.
  • DDR2 sad to say
  • Im still using ddr2
  • Clock speed is in MegaHertz and it is the number of millions of signal changes in a second
  • My laptop uses DDR3 memory. It came with 2GB and I added another 4GB. It's working pretty well for everyday tasks :)
  • If you could also upgrade the HDD to an SSD (assuming you haven't done so yet) you'd be amazed at the performance of the average laptop
  • I've done this and I was blown away. Great investment :)
  • Yeah, I upgraded it two months ago! I really made it a lot faster, and with the ram upgrade it acts like it a new low-end laptop (instead of an unusable old one :P). Plus, windows 10 works better than windows 7 on the same hardware, so that helped too. :)
  • Check your board specs, you might get a larger gain by getting another 4gb stick (of the same make/model/part # of the one you already have), and letting it run in Dual Channel mode. Requires a matched pair. Note: not all boards/cpu's support dual channel, but most do. Think of it like RAID 0 for your ram :)
  • Dirty lie. What manufacturer puts in 2gb of ram when the PC is 64bit? You said you added another 4gb making 6gb ram. 32bit can't have more than 4gb ram. Or did you mean you have a total of 4gb ram and not 6? If your PC is indeed 64 bit and came with 2gb ram, then that manufacturer has serious problems
  • Actually, I do have a Toshiba Satellite 64bit Intel Celeron Laptop that only has 2 gigs of ram in it. It cost me $299 band new when Windows 7 was launched. (2009). It doesn't perform that well. (Gee, I wonder why) I could give it SSD and more ram to spice it up though. The Ram is Single Channel DDR3 clocked at 800mhz. Yes, it's slow.
  • I am using DDR3L with 850 Evo SSD. Cant believe the performance difference with and without SSD. Just login and launch the favourite apps they open instant. No more waiting to load the background services...
  • Got 64G of DDR3 2400MHz and will stay that way, the tower is totally tricked and will live forever.
  • Daaaaaaamn, Daniel. It's rare to run into someone reppin 64GB of ram...youre my hero
  • I just put in (8 x 8) Corsair Vengeance white LED.. Not because I wanted 64gb, but because my motherboard had 8 slots, and the vengeance didn't come in 4gb sticks. Purely aesthetics.
  • Rocking 32gb of Corsair Vengeance OC DDR4 memory in my X-99A machine.... with a intel 5820 CPU.... My gaming machine... The CPU is rated at 3.3ghz(6 core), but, with a minor overclock (mega fan) runnng at 3.8ghz. Also have a GTX970... Runs everything I dump at it runs flawless resuts @ 1080p (my monitor) with out a signle sudder... Epic machine.... hand build by myself :)
  • 32GB is overkill, just for gaming. It would be worth getting at least Ultrawide 1440p or 4k monitor for those specs, 1080p is kinda crap.
  • To each their own... Last gaming machine I had 8gb, I was going to go to only 16gb but, I found a deal that I could not pass up (figuring I would not need to worry abouot expanding memory in a few years). Alhough it is my gaming computer, it is also a office/some work machine too. I do VMs on it and lots of custom hardware so more memory is always nice. I can run 3-4 VMs on Vmware workstation pro... XP, Win7, iOS and Win10...and the host OS does not see ANY slowdown... A nice perk of having 6 cores and 32gb of memory. And when I built this machine, a NICE (not a cheap-o budget one) 4k Monitor was starting around $700... So  my $250 1080p monitor looks awesome, when I do my next round of upgrades (maybe mid next year), I will upgrade the 970 and the monitor to a higher res..
  • Potentially not for VR though.  Say you have 4 slots, you can put 4x4 to get 16 gb now... but then for VR you may want to upgrade that, in which case you will have to spend additional money to replace all 4 sticks with 8x4 to get 32 gb.  That's very expensive as you are replacing a whole set.  I decided just to get 8x4 now as I will likely get VR when Vive 2.0 comes out.
  • Was thinking about going the VR route but, been playing with VR with the cell phone.... Meh, ok. Dont want to spend $600 on the Oculus Rift right now.  Not sure if I am going to love it or not. I need to see some more mass acceptance on games and right now, very limited. My motherboard has 8 ram slots (X99A motherboard), Right now filled up with 4gb chips. The motherboard supports a max of 128gb but, dont think I am going to go that way any time soon.  If I wanted to upgrade, I could replace some of the 4gb chips with 8gb but, I think for now, 32gb is more than enough for a gaming /office machine
  • Memory access speed is also dependant on whether it's running dual channel/quad channel, as this affects the bandwidth