Precision 7520 memory and storage upgrade

[TheChev]

I just purchased a Precision 7520 configured with i7-7700HQ Processor, 15.6 Inch UltraSharp UHD IGZO(3840x2160) Display, 16GB DDR4 Non-ECC SDRAM 2400MHz (2x8GB), 1TB 2.5Inch SATA Class 20 SSD.  I want to increase memory to 32GB and add an additional 512GB or possibly 1TB drive.  If I don't replace the existing memory sticks, I assume I will be limited to 2 more sticks of 8GB DDR4 2400MHz memory in the second 2 slots.  I'm also a little confused on what my limitations will be for the additional HDD or SSD.  Can someone please offer me some enlightenment on what my options are?  Thanks...

[ejn63]

You can add an M.2 SATA or NVMe 2280 SSD -- that's the only form factor you can use (there is not space in the system for two 2.5" drives).

[TheChev]

Thanks.  What about the memory?  I had a Dell Tech tell me that I could add a single 16gb stick to my existing 2 8gb sticks.  I've always been under the impression that you had to increase in pairs of equal size.  Same tech told me that I could add 2666MHz memory to my existing 2400MHz memory.  Why would I do that since the system would only utilize it at 2400MHz?  It's kind of made me lose confidence in Dell techs.

[ejn63]

You don't have to add pairs but for best performance, you should due to the dual-channel design.

Most faster RAM will downclock (but it's always better to buy RAM certified to work in your system, than on specification-- Crucial, Kingston, Corsair, etc. have tested/certified RAM for specific models).

[TheChev]

Thanks again.  You've been a big help.