I had a bad experience years ago with Corsair memory and I refuse to use them ever again. Kingston and PNY? Too many problems getting replacements for both. Get burned once by a company or a manufacturer and they'll be hard pressed to get you back as a customer. I've never had a problem with Crucial so that's the only memory I use now.

One of the most difficult things I've ever had to identify on a new PC build was having a faulty CPU. I knew I had a hardware problem and after swapping out the memory, the power supply, the hard disk, and the mobo, the only thing left was the CPU. Sure enough,after replacing that everything was smooth sailing. I'm still using that PC today.