dual Xeons OEM ??

[INFRNL]

I do not think overclocking voids it as long as you stay within all the limits of the cpu, but I could be wrong. I can say out of all the cpu's I have had; I have not had 1 fail from overclocking, ever. I think the only way you would fry a cpu is if you go extreme with voltages or if you do not keep an eye on your temps.
For 4ghz range should be fairly easy with the cpu's you have listed. Just make sure you use good aftermarket coolers or h2o.

as far as oem; Origin is correct; only difference is warranty and HSF

also make sure you use a good thermal paste. everyone here has their own opinions. I like arctic silver 5 or IC diamond

[lopium]

ok thanks a lot for your answers, actually you helped a lot.
i sent an email to intel for knowing about warranty issues if I OC the cpus, waiting for an answer right now...but i'm quite sure i will take OEM ones, something like 300 - 400 $ difference/cpu...it's a lot of money!

[Buckeye]

Also to consider

Retail CPU's that come with a box, not sure if these Xeons come with a cooler. But RMA for them goes through Intel.

OEM RMA's go through the place of purchase, like Newegg for example.

If you get them from eBay I am not sure how RMA's would be delt with but I highly doubt Intel will.

I am not 100% sure about that, but it's something you might be interested in looking into.

[runmc]

Intel doesn't warranty OEM but I doubt if your going to kill them. You will get no warranty what so ever if you buy from eBay. If you buy OEM through a store like Newegg, you will get the 30 day warranty.
There is always a risk involved will buying eBay.
If you want OEM go through Newegg or other good online store.