DDR4 in DDR3 motherboard, why is it working?

I'm using 8G of DDR4 memory in an ASUS M5A78L-M/USB3 (spec: https://www.asus.com/us/Motherboards/M5A78LMUSB3/specifications/). The spec says it supports DDR3. Why is it working? I must not understand the difference.
Who is Participating?

[Product update] Infrastructure Analysis Tool is now available with Business Accounts.Learn More

I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

Dr. KlahnPrincipal Software EngineerCommented:
DDR4 and DDR3 are not interchangeable.  In fact, the cutouts are placed differently and it should not be possible to install DDR4 into a DDR3 socket.  It's possible that there is a typo on the manual.
Shaun VermaakTechnical SpecialistCommented:
As pointed out above...

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
MarkAuthor Commented:
OK, you're right! I was sure I had bought DDR4 and that's what I had in my parts-list notes. My notes were wrong. Thanks for the great illustration!
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Server Hardware

From novice to tech pro — start learning today.