5040 MT 2nd Drive

 there is no limit,

try to know that books say 10 years  old can not see the future, and 16TB HDD, not invented yet,

and do work. by not accident but by DESIGN.

that is what SATA gets you read the wiki on SATA it's all there.

the boot drive has a 2TB limit for  not using UEFI, GPT formatted disk, but not the non boot drives,

you can have 26 lettered drive, you can go more (volumns), with USB< or eSATA ports, endless, I can plug in 10 USB drives on most PC,

or and 6 more USB ports with a card and and plug in 6 more. or  add sata cards. 

the only limit is SLOTS (and speed)

you can in fact put any 2.5' driven in any 3.5" bay with a simple $1 adaptor..

you  can in fact, add 2.5" SSD with added mounts inside any large case like we have, MT..

SSD has no motor so , no fancy HDD mounts needed,  $1 mounts work great, heck even tie wraps..!!!

the limit on DELLS is the silly lack of SSD/HDD power cables,  but there is cure of that too.

most things have cures. ask.

Welcome to the Dell Community  @DaveXTR 

After all that I'm confused???

I thought I could clear up some things by looking at the manuals???

Well that just confused me even more???

Table 9. Drives.Feature Specification

https://www.dell.com/support/manuals/us/en/04/optiplex-5040-desktop/opti5040mtom/specifications?guid=guid-442798b9-2c5a-4dcb-87c3-8dc387625675&lang=en-us

(5.25-inch drive bays) that has to be incorrect they should be 2.5"???

I do believe I have a few 5040's at my warehouse but I am not sure if they are the MT or SFF.

Let you know what I find tomorrow.

Best regards,

U2

That drive size is correct for external. The drive bays for DVD/cd rom drives are that size. You have to look for internal drive bays. They will be listed at 3.5 or 2.5. if there is only 1 internal drive bay you can use an adapter to run 2 2.5" drives in 1 3.5" bay. You can also buy a number of adapters to run multiple 2.5" drives in a 5.25 bay .

Welcome to the Dell Community  @frankr2994 

For now looking at the Manual and Specifications it seems like there is a 3.5" and 5.25" CD/DVD slot.

The 3.5" that would slide out the front and the 5.25" that slides out internally.

Again looking at the M&S I can not see anything specifying "Internal Drive Bay"???

Did you see something I missed???

Or do you think the manual is incorrect???

Well like I said I think I have a few 5040's at work and will post what I find.

Best regards,

U2

Ok you win lol. Very confusing manual. I tried looking at pictures and I can't tell what they have going on. With a system in front of me it would be obvious and well you know that lol. 

Thanks for the responses. Well after reviewing a couple videos and assuming the info presented therein is correct I think the answer is the primary bay; which also holds an optical drive, takes a 3.5 inch and the expansion bay takes a 2.5. The smaller ssd/hdd is a safe purchase b/c as one person already mentioned, you can adapt the smaller of the two options to fit inside a larger bay. 

I still cannot tell whether the expansion bay takes one or two storage devices but will figure that out after I crack open the box.

Awsome! Thank You