Most of the negative feedback in New Egg is user error, I don't shop the others. I also have MC near by, but not close. New Egg has about the best prices, but you can find better on other sites if you search.
Philly is correct.
For motherboards, the 5-egg reviews are lower because it requires more user involvement for proper configuration. People who lack patience or experience are going to have trouble even with a stellar product. That's a behavioral dimension to understanding customer reviews, and there are more.
If users/buyers aren't happy with something -- whether due to their own ineptitude or a manufacturing defect -- they have a bigger incentive to post a customer-review. People who don't find fault with the product have less an incentive to provide feedback.
So the 1-egg and 2-egg reviews will have a serious bias as statistics indicative of quality-control percentages. The reviews will show considerably greater "defective" percentages than the actual QC rates for what's coming off the assembly-line.
Customer reviews -- if the accumulated sample-size is big enough -- may be a way of assessing what sort of problems you might expect, and what caused those problems.
Barring "DOA" events, if a buyer suggests that something "didn't work," you might look more closely at the review to find out the product wasn't compatible with the OS he was using, but someone else may give a glowing report for your own OS choice. But here -- I digress.