Upgrading CPU (and mobo?)

[Meong]

I'm currently using Core i3 540 @ 4.00GHz 1.21V which runs really hot (reaching 100+C on stable test), sometimes it will even turn off by itself after stress testing for awhile (too hot). Assuming normal conditions are't anywhere near that stress testing, I guess that'd be OK. Well, I do some virtualizations and some crazy multitasking (sometimes 140+ processes at once). So that's why I came here to ask. I'm looking to upgrade my CPU. I can still buy a new heatsink (costs $70 for heatsink + new case) (current : stock). So by the way is buying heatsink and overclock further better, or Is the i7-870 with the current mobo the best option? (costs about $240 here), or the i7-2600K ($280(CPU)+$130(Mobo)) ?
I need the multithreading capatibilites since I do extreme multitasking and virtualizing.
I want it to be cost-effective. I'd choose i7-2600K but I'd like to know if buying the new mobo is worth it as both have 4c 8t. I'm just confused will I get into the advantage of the 2600K overclocking potential?
RAM is 16GB @ 1330MHz 9-9-9-24 CR2 => 1740MHz 10-12-12-32 CR2 (OC begged me to loosen it) 1.6V
GPU is 9800GT (also looking to upgrade) nonOC
Mobo is H55M-UD2H
Still using HDD. Need a lot of storage, SSD won't fill my need at the cost it gave me. Superfetch helped btw.
Computer is for online gaming (20 open at once @400mB ram usage each) + *some* little heavy gaming (but i have alot o games w/ it's setup lol) + intense multitasking + *some* 3ds max and video rendering.
Thanks for your attention. Well, any advice?

 

[Robi_g]

what do you mean by intense multi-tasking, what programs are open 'cos I (sort of) 'extreme multitask' with 3 word documents, a few spreadsheets and 6 tabs open in Chrome but I don't need a decent CPU for that.
If you can afford it get the mew mobo and i7 2600k, if not then buy an i5 2xxx and new mother board and upgrade later, either will be better than the i3 you currently have

 

[Meong]

That multitask.
Sometimes 50tabs on firefox.
20 online game clients open up at the same time.
Much messengers + Dropbox + Antivirus + uTorrent, etc.
And so much more startup processes (a total of 16 items on bottom right bar)
iTunes open 24.7 / autosync
Documents
Sometimes editting a Crysis level
and
Sometimes virtualizing while doing all above
Current processes is 138
Not running VM's, mem usage is 8GB
I usually run VM to have a Windows running seperately for the iPad (iPad controlling the VM, much like Windows on iPad, lol)
FYI, I hate the close button. 😀