Memory Upgrade for HP Envy 700-230

[KhanWasFramed]

Hello, I have an old HP Envy 700-230 PC.  (i.e. not a laptop) and don't know much about memory.  Just experimenting and want to add another 8GB RAM.   

Question 1: Right now on Bank 2, I have installed:   M378B1G73DB0-CK0 Samsung 8GB PC3-12800 DDR3-1600MHz non-ECC Unbuffered CL11 240-Pin DIMM Dual Rank Memory Module.   This according to the HP Diagnostics.   Visually confirmed by me.  

However, the online HP specifications for this PC under "memory upgrade information" suggests my computer has: "Two 204-pin DDR3 DIMM sockets" that supports "PC3 12800 (1600 MHz)"   HP ENVY 700-230 Desktop PC Product Specifications | HP® Customer Support

I understand that the 204 pin DDR3 is for laptops, whereas the 240 pin DD3 is for PCs.  Is the type of memory in the online specifications a misprint?  

Question 2:  Is it true it is problematic to mix two different brands of memory if clock speed is the same?  In otherwords, does it make more sense just to buy two sets of 8GB replacement memory for this, if I can't find the exact Samsung model ?  Thanks!!

[Prométhée]

indeed there may be errors, so if you have already changed the module, do not pay attention to it
you can mix module from different brands
even if sometimes there are problems, most of the time no worries, see here, good examples:

upgrade computer h9-1228ef mot...