Girl needs help with built in standoffs? mobo mounting

Hello, I am building my computer and I am used to using standoffs for all of the eyelet holes in the motherboard because the past cases I have used the motherboard mounts directly to the back of the case using all standoffs.

This new case I got however is a little different. rosewill r226-p-bk

http://www.newegg.com/Product/Prod [...] 0&Tpk=r226

It has what appears to be raised areas (as you see in the photos) and then a few valleys if you will where I can use standoffs to secure the motherboard. The raised areas appear to be metal and the mobo I have fits perfectly when screwed directly into these raised holes. The IO plate also fits. I cant use standoffs on all holes because then the IO doesnt fit. So, my question is, do I use plastic washers to be on the safe side, or is it safe to just directly mount it to the raised metal area?

Please help

I wouldn't think plastic washers would make a difference; the screw securing the motherboard would conduct to the case anyway.

I would just follow the instruction manual.

And +1 for using your gender to get the attention of a bunch of geeks.