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Dell optiplex cases

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Dec 9, 2003
Orlando, FL
I've been looking at some Dell optiplex cases on ebay and they seem very cheap and from my experience have good construction.

Is it possible to get one of these cases to fit for a mATX motherboard and standard PSU found on newegg? If not, would it be impossible to mod the case for it, and what form factor do the Dell cases use?

Ideally I would like the smallest form factor optiplex or vostro case that fits a mATX motherboard and standard PSU without any case modifications.


New Member
Mar 3, 2005
The full size cases (On both the clamshell all-plastic model, and the newer model with metal sides) will support a standard power supply. I had replaced the power supply in an old Optiplex GX260, but had to cut out some of the metal for the switch on the power supply to poke through (the OEM power supply doesn't have a switch, and the metal on the case covers most of it).

For the desktop-style cases (medium sized, can lay flat on the desk or stand up straight), standard power supplies will not fit. For the older clamshell-all-plastic ones, they use a thin, skinny power supply, leaving room above it for the PCI riser card. For the newer ones with the metal sides, they use a small one, located behind the HDD/CD-ROM drives.

I should also note that the newer optiplexes use BTX motherboards. There should be room for the mATX board, although I'm not sure if the stand-offs for the screws will be placed correctly. Plus cable-management, etc...

tl;dr older cases: all plastic, clamshell, ATX; newer cases, metal top and bottom, BTX. Towers for both should support standard power supply (might have to cut metal mesh).

Hope this helps.


Dec 25, 2004
We have the 755s at my work. The motherboard is set up more like a BTX. I can take some pics tomorrow and post them.


Dec 25, 2004
Firestrider, here is the inside of an Optiplex 755 case looking at the motherboard:



Senior Forum Spammer
Jun 6, 2002
Thanks for the picture torin3.

Yep, it looks like the standoffs are not compatible with mATX :(

well that model wont be but another might be... BTX vs mATX huge since the cpu is placed up front vs back like ATX/mATX/mITX.

even if the standoffs didnt work, why not mod the case to make it work?