can i put a intel i-7 377k in one of these babies or no?

This forum post has more information. There is a bit of confusion though. The moderator refers to this list of compatible CPUs based on the Q77 chipset. In that list the i7 3770K is shown. But the Dell technical guidebook here for the 7010 does not list the K version. Since the moderator lists the K as compatible I would accept that answer and it is worth a try anyway. One question though, which format of the 7010 do you have such as SFF, USFF, MT, DT?

JOcean raises a good point.

Re: can i put a intel i7 3770k in one of these babies or no?

Absolutlely

 The i7-3770k is definitely compatible with 7010 mt/dt/sff.  

1. Userbenchmark has validated 3770k.

2. 3770k and 3770 have identical cpuid and will be accepted by dell bios

3. Dell does not validate 3770k (used in Aurora r3 only) because it is a premium cpu reserved for gaming pc.  Dell optiplex bios cannot fully take advantage of k cpu either due to business class chipset lack of OC support.

nevertheless the 7010 motherboard is 100% compatible with 3770k.

PS

If it were 7010 USFF it is designed to run a low power cpu (e.g., 3550S, 3770S, both 65w tdp) due to its small cpu cooler.  motherboard still compatible w 3770k but practically the case/cooler supports up to 65W cpu.  both 3770/3770k have 77W tdp.

So will have to upgrade the power supply if it is 77w or will the board not support the power 

I am thinking doing the same i have optiplex 7010 sff with i3-3220 

i want to upgrade the cpu(processor) performance but i don't know if the i7-3770 or i7-3770k will work directly or do i have to change the psu to support the new processor 

If new psu is required please suggest one 

and also do tell if the upgrading worked out for you 

Optiplex motherboard chipset and bios do not support overclock of -k cpu. 3770k cpu will run at base frequency.  The mt/dt/sff board/psu have no problem supporting a slightly higher tdp cpu such as 3770k.  The Dell cooler might need to be upgraded to 95w performance grade heatsink for better cooling since the mainstream oem stock cooler (pancake) is rated for 65w tdp and has a aluminum cold plate.  many ideas of cooler upgrade out there in a 7010 tower.  easiest one may be the XE2 copper based cooler.

7010 oem cooler

I have an old Optiplex 7010. Can anyone tell what CPUs I can upgrade this box to, currently dual core only. It would be nice to go quad or higher. thanks for your help

Did you read this thread?  Top spec CPU is i7-3770, but it can also run an i7-3770k.  Note that Dell BIOS does not have OC.

JOcean already linked the Tech Guide toward the beginning of this thread.