Rebuilt PC, got black screen and beeping

[Funtoink63]

I swapped my old motherboard (with cpu ram and cooler) and after turning it on I get black sceen and 3 long beeps. Manual says nothing about the beeping. What does it mean?

 

edit: new system specs

cpu: intel i7 7700k

motherboard:asrock z270m-itx/ac

ram: 16gb (2x8) kingston 3000mhz cl15 ddr4 fury

cpu cooler: coolermaster hyper 212x

cpu paste: thermal grizzly kryonaut

[Glennieboyyy007]

which mobo, cpu, ram? try only one ram stick and try all the ram slots one after the other to see if you got faulty ram

[Funtoink63]

3 minutes ago, Glennieboyyy007 said:

which mobo, cpu, ram? try only one ram stick and try all the ram slots one after the other to see if you got faulty ram

added to first post, will try

[Glennieboyyy007]

maybe try this site or this one

[Funtoink63]

appaprently it was not fully inserted ram module/s because I tried to take both dimms out, put one them one by one and pushing as much I could into slots and now its working, with both dimms. Because there are no latches on the other side (it just slides it) I thought that they were fully inserted. thank you @Glennieboyyy007 for pointing it out.