I bought new RAM cards for my computer. The first pair didn't work, so I compared them with the ones my computer came with; the new ones were 3000MHz, and the old were 2400MHz. So I returned the 3000 ones, and ordered new 16gb (2x8gb) 2400MHz ones from Corsair. No matter what I do, the computer will turn, the hard drive will make its usual slight noise of booting up, the fans will spin, lights will come on... but no keyboard, mouse, or monitor. And then the computer will quickly shut back off, and continue doing this over and over again until I turn it off again and put the old RAM cards back in.