System manufacturers purchase processors from Intel in bulk trays. They are thus often referred to as 'tray processors'.
Ofttimes, manufacturers will have some number of these processors left over. They try to recoup at least part of what they've paid by selling these left-overs on the gray market. The problem is that only the original purchaser (i.e., the system manufacturer) has a warranty for these processors; the purchaser on the gray market do not have a warranty - and they only find this out when they have a problem and try to get it replaced.
You get what you pay for. You can legally purchase a tray processor - and it will often be much cheaper than if purchasing a boxed processor - but you will not get a warranty for this processor. Most of the time, this works out ok, but when something goes wrong, well, you are out whatever you paid. Secondly, there are a lot of shenanigans that go on. Often, used processors are presented as being new, unused processors. They work, but they may have had a hard life so far and not much lifetime left, or they are simply duds that do not work. It is thus important to purchase tray processors only through reputable services so that the processor can be returned if it doesn't work as advertised.
There is another thing to be worried about. Early in the new processor release process, Intel will provide, free of charge, Engineering Sample and Pre-Production processors to companies to use to test their new motherboard, laptop and system products. There are lots of unscrupulous folks, mostly in China, that will illegally sell these samples misrepresenting them as new or used - but production-level - processors. I say illegally because these samples are given to them free of charge on the proviso that they are never sold; that they are either destroyed or returned to Intel once the manufacturer is done with them. The issue with having these processors is that they may have errata that cannot be addressed by microcode update. They may appear to work just fine - for a time - but could fail if a certain operation or particular ordered set of operations is performed.
So, there you have it. You can now make a fully educated decision.
..S
