ya ram requires to snap into correct channel per stick as you need to snap your 4gb into socket 1 or 3, then the 8gb into socket 2 or 4.

sometimes the board can Auto negotiate the ram connection but only the ultra high end ones.

is a good thing you talked to an instructor to solve it, but if you looked up the Beep codes it would tell you the ram you placed are in the incorrect slots.

And I read somewhere that the bigger one needs to be in the first slot. My laptop had 2 slots, and so I put the 8GB where the 4 was.

My instructor said the beeping code was for the cmos battery. I remember disconnecting and reconnecting it several times during the process, but it was connected properly. Dunno why it beeped, cause I didn't touch it after I had it put back together.

sometimes with motherboards they beep cause the ram config is different and a cmos reset is necessary to fix.

it does not matter what sizes go were for ram, as long as the same SET that is a kit or identical twin ram sticks are slotted in parallel, no mater what ram yo put your system will clock to the ram that is the slowest speeds and latency, for example you placed two good 4gb 1600Mhz ddr3 ram in slot 1 and 3 to equal 8gb on channel one, wile you slot 1200mhz 2gb ddr3 ram in the 2 and 4 slot in channel two = Profit! lol no but the pc will clock itself to the 1200mhz speed only

this is call Asynchronous memory as in is unbalanced and system will clock to the lowest ram in all channels.

you can get away via adding same speed ram and same brand, wile the Memory on em can be different, but if you want FULL 128 bit full speed ram you need to get what they call Kit ram, they are built to work as long as all the ram in the kit is placed, this eliminates any lag or latency on ram to maximize pc performance as well as removes the bottleneck in your system.

Most folks i work with in the rendering area and graphical arts they require kit rams as the Asynchronous memory puts a huge damper on the pc.

if its a laptop, you need to Check your Laptops's manufacturer limitations, most laptop now days can go upto 16gb, but laptops back in 2014 and older could only go upto 8gb as they are not able to configure the lower cpu speeds and architecture of a mobile based CPU.

also Some laptops, HP, Dell, Lenovo, are notorious to reject certain brand of Ram, is why i have a stack of Hynix ram as there accepted on all 3 laptops, i know Lenovo is particular fussy with ram types and speeds.

Glad it didn't explode on ya.

I'm not a tech guy, but good for you that it all seemed to work out