Can I use 2x4gb and 2x8gb ram

[e.sgk1]

I have a ASUS 797-P Ver.2803 motherboard which I have been running with 2x 4gb ram for a year or so. I recently upgraded to 2x8gb ram (Both from the corsair vengence DDR3 series) and I was wondering if the motherboard can run 24gb ram total.

When I initially installed the new sticks of ram I left the onld ones in so that from slot 1 - 4 is went 8gb, 4gb, 8gb, 4gb. When I tried booting up my computer I think it messed up the graphics card somehow because I usually need my mnonitor on digital 2, but I could only switch between digital 1 and RGB. I put the cable in the digital 1 slot and then found I could only switch between digital 2 and RGB.
I then took out the old ram and put the new ram in slots 2 and 4. The computer then took a little while to boot up but has now done so and everything is fine.

I'm just wondering if anyone can tell me if I can put the 2x4gb ram sticks back in without killing my computer somehow. If not then I will be able to sell them.

Thanks in advance

 

[Zerk2012]

If you have this board I thnk you mean Z97-p
https://www.newegg.com/Product/Product.aspx?Item=N82E16813132229
It supports 32GB of memory so yes if the memory will work together could and could not.

 

[e.sgk1]

I knew it supports up to 32gb of ram, but with most computer things I wasn't sure it it had to be really specifically 4,8,16, or 32, like doubling each time and 24 not being an option.
Does anyone know which slots it might be best to try these out in?

 

[Zerk2012]

The memory you have now should be in the right slots to be in dual channel so use the other 2 slots.
if the original memory was in the gray slots then put the 8X8 in them and the 4X4 in the black slots.
You can use both sets if they will play nice together.

 

[e.sgk1]

Hey, So just for the record my Motherboard doesn't have colour coded slots. But I have put the 4gb sticks in slots 1 and 3, and the 8gb ones in slots 2 and 4. My computer seems to run fine, and the DXdiag says 23.9gb of ram are in the system.

Just a small note to anyone else who may be having a problem, the first time I loaded the computer up it behaved very strangely, but then after resetting it it started up just fine.
When I first put the 2x8gb in the computer took a lot longer to boot up, I assume the change in ram had confused it a bit. But I'm just noting this all here in case anyone else is in a similar situation to me.

Thanks for the help