not overclock - buy retail
overclock - must buy retail - they don't care if you burn it by overclock or put in microwave, just don't make physical damage or cut the bridge. $15 more for easy to abuse warranty for 3 years - what a deal!
retail advantages:
less chance of buying remarked cpu
3 years easy to abuse warranty
protection box for shipping the cpu to someone else if later you want to sell it
installation instruction manual
good HSF (intel uses sanyo denki fan)
logo sticker
if you want oem, don't look at the warranty, just look at the lowest price one.
15 days, 1 month, or 1 year or even liftetime doesn't matter if it's not by amd.
if you damage or burn it, do you think the seller will give you a new one generously?
don't believe the warranty from the seller.
cpu doesn't go bad easily, when it works from the beginning, it'll probably work forever.
that's why some sellers only give only 15 days warranty on oem cpu - they know if it doesn't work at first, it's bad, must replace another one for you.
that's also why some sellers give 1 year warranty - they know if it works at first, it'll work forever.
because of improper installation and improper cooling can damage the cpu easily, some sellers give 1 year warranty if you also buy the heatsink and fan they like, otherwise 15 days.
for insurance, it's better to buy retail/BOXED, 3 years warranty from amd, they won't care if you damage or burn it, they just give you a new one if you request rma. the price difference is so small, and you get a heatsink and fan good for normal operation.
if you don't intend to buy a better heatsink and fan like vantec, globalwin, alpha, etc. those over $20 kind,
don't get oem cpu with cheapy $10-15 heatink and fan, get a retail/BOXED instead.
however, it's still ok to buy oem, must use credit card with purchase protection. in case of damage during installation, let the credit card company eats it if the seller knows it's damaged by you instead of DOA and refuse to warrant it.