Standoff screws not tight enough

[ReggieKray]

So I bought a PC build off pcpartpicker, and being a fairly noob PC builder, I tried screwing the standoffs directly into the motherboard to the case. Sounds extremely stupid, I know, but then I tried the proper way by screwing the standoffs into the case and putting the motherboard on top. The only thing that went wrong after that was that the screws that I received to put into the standoffs didn't screw in properly. Only a couple near the corners of the case screwed in properly.
As a result, the motherboard was unstable and when moved, the screws would fall out of the standoffs. I tried applying pressure and replacing the standoffs, and ensured that there were no extra standoffs screwed in. Even so, there was an 'infinite loop' while screwing in.
I hope I don't put anyone off answering this question, because of its sheer stupidity, but I really need help on this one.
The case is NZXT S340 White
The mobo is ASROCK AB350M-HDV

 

[USAFRet]

" the screws would fall out of the standoffs. "

You used the wrong screws.

 

[ReggieKray]

" the screws would fall out of the standoffs. "

You used the wrong screws.

There were only one packet of screws that correlated with the standoffs, even so I used every other screw for every other bag and tried to mount the motherboard with them. I'm a noob, I know, but I have used whatever options I have seen until now. Hoping someone experienced can give a better answer. Thanks

 

[USAFRet]

" the screws would fall out of the standoffs. "

You used the wrong screws.

There were only one packet of screws that correlated with the standoffs, even so I used every other screw for every other bag and tried to mount the motherboard with them. I'm a noob, I know, but I have used whatever options I have seen until now. Hoping someone experienced can give a better answer. Thanks

The standoffs, being brass, is nearly impossible to strip out.
So the threads still exist in the standoffs.

The screws, if the correct size and length, should screw in and allow themselves to tighten up.
And it would be almost impossible to strip the screw threads with just finger pressure.

Take the motherboard out.
Try all the different size screws, just going into one of the standoffs.
See what happens.

 

[ReggieKray]

The standoffs, being brass, is nearly impossible to strip out.
So the threads still exist in the standoffs.

The screws, if the correct size and length, should screw in and allow themselves to tighten up.
And it would be almost impossible to strip the screw threads with just finger pressure.

Take the motherboard out.
Try all the different size screws, just going into one of the standoffs.
See what happens.

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I've also tried that, and the screws tighten properly in the standoffs. If I cannot gain a solution by the morning I'll order an entirely new case.
Thanks for the help in advance, guys.

 

[Karadjgne]

You can buy new screws and new standoffs far cheaper and faster than replacing the case, unless it was a walk-in purchase.