Stacking

[felix107]

HP ProCurve 24 Port A5120 24G E1 (JE068A)
H3C S5120 48G-POE E1

Hi wanted to know if these two switches can be stacked?

Any input would be greatly appreciated. 

[parnassus]

With "E1" you really mean "EI" (A5120 comes as EI or SI series), right? if so...creating an IRF fabric (what you call simply stacking) using *same* switch series (EI with EI, like for like...which is correct and mandatory [**]) is good, doing that using identical Switches with different branding (as example: HP versus H3C or vice versa) is not a good idea (for various reasons): Speaking about implementing IRF fabric, HP recommended to (re)brand H3C into HP and then use a common HP software version (possibly the latest available for the Switch series considered) on any switch that will be member of the planned IRF fabric.

In other words (directly from "HP Series Switch & Router Brand Migration Feature Guide"):

"Different Brands used in a single IRF fabric

Some HP, H3C and 3Com switches can form an IRF fabric, and their MPUs are interchangeable. If differently branded MPUs are used on your switch or IRF fabric, change the MPU brand to be the same to prevent an active/standby MPU switchover or master re-election from causing network management problems. Network Management systems may detect unexpected changes such as new device information (vendor name, device model, and device panels) changes and force re-collection of information about MPUs and other hardware components. For example, if an IRF fabric uses an HP switch as the master member switch and uses an H3C switch as a subordinate member switch, the network management software will identify the switch as an HP IRF fabric.

Then, if the IRF fabric is rebooted and the H3C switch is elected as the master, the network management software will identify the IRF fabric as a new H3C IRF fabric. To avoid this problem, change the brand names of all member switches to be the same".

[**] except for corner cases: Switch Series that support Heterogeneous IRF, like 5800/5820X and 5900/5920 (read here).

[Vince-Whirlwind]

Just a note: the 5120 is never a Procurve, it's always 3COM, so it can be branded H3C or HPE, not Aruba or Procurve.

If it's the same switch, IRF should be fine.
If you can load up identical firmware on them both, then they are the same switch and you will be OK, providing you implement the IRF exactly as per the IRF documentation.