I think you guessing it right. It's either mobo or cpu. Cause you overclocked the thing. If you have no other mobo or cpu to test then bring both to the shop where you bought the system. They should be able to help you test and see which is faulty. Depending on which shop you bought it from. Some shop will not test for you and some will give stupid excuse. Hope you bought it from a good shop.

Dont worry, if mobo prob then just send it back to RMA. I RMA my S3 before. As long as no burn mark then they will accept RMA one.
But seems like ur PSU might have some prob.

if running default setup oso got pr0b?

hmmm happen to me before,but it because wrong bios flash...on...offf...on...of never post oso until it burn my 7950gx2...so sad...then send both to rma and get back my board and flash it to f10 and been runing 24/7 until today for 1 week plus edi....
so in your case just rma it la...
oopss didnt see ur post on top there...good rma edi..so wait la...buy a chepo board for backup lor...

really? then my bios flashing last time should be incorrect. no wonder when in windows, everest,system information,sisoft sandra showing my bios version is F5 but last time i had flashed it with the F7. but the post screen showing F7 

hmmm but i think this happen coz you dont reset the dma pool or sumtin...you know when you flash bios...some of the other software will say it the old bios version before flash,but boot up will show your true bios...but i think this is normal...since you dont erased the dma thinggy..
take a look at the attachment below as you can see:
the bios is f10 but dmi pool detected it as f3....this is actually normal thing nottin to worry bout...taken directly from everest...

Can i ask one Q .. what's RMA?
My computer has a similar prob now .. duno what's wrong .. I on my pc, the cpu is running but it never show anything in the monitor. It doesnt go on at all either than running the pc(dunno run for what .. the fan is moving and stuff)

If monitor got prob, also couldnt be coz my keyboard has no signal as well ... What's wronggggggggggggggg? Can someone plz tell me ........?? HELPPPP

A Return Merchandise Authorization or Return Material Authorization (RMA) is a transaction whereby the recipient of a product arranges to return defective goods to the supplier to have the product repaired or replaced or in order to receive a refund or credit for another product from the same retailer or corporation. In many of the cases a RMA is generally given after a series of testing for Eg: for a Hardware product, if there exists a defect in the product, the engineer on the call will have to analyse whether the hardware suffered a CID (Customer Induced Damage). This is done to generally not accept the losses on behalf of the supplier due to negligence from the retailer. The product then goes to the scanning vendor who will try to repair the defect in case it is a minor defect and replace it in another order that he gets. If both these tests fail, then the good is sent to the principal vendor for replacement and the principal vendor will again check whether there were any defects in the product or whether the product has been tampered with and finally if all the tests fail and there is a general production defect, the supplier replaces the material with the same material which is not defective or he issues a credit note to the customer or the retailer that can be reimbursed at a later point in time.Also good for exchanges.

Generally, this is done with goods that are new and have been received DOA ("dead on arrival") or when they have become defective while still under warranty. The customer generally calls a customer service phone number and gets an "RMA number" or designation which is written on the bill of lading or other packaging. This is so that the supplier's own shipping and receiving department knows how to route the returned goods and is assured that the customer has talked to someone in customer service.

The specifics vary from one retailer to another and between industries. In some cases the retailer sends RMA forms and packing labels, sometimes even shipping packaging for the return shipment. The labels may provide for the retailer to pay the shipping charges, e.g., by freepost.

It is often a lengthy and highly bureaucratic process which is inconvenient to the customer.

Regardless of the details, the process is referred to as an RMA. Sometimes the term is informally used as a verb: "I'll have to RMA that new system because it was DOA."

oh.. it is normal la? hmm nvm lah just wait for my board from RMA and c how first. btw how to erased the dma thingy?

I think u need to disable those o'c setting b4 flash BIOS.
3 Gigabyte users in C2D o'c board killed thier mobo becos dint set default those o'c setting b4 flash BIOS. Im the 1st one then kaiser_falco and blaxez, now u are the forth victim. 

if u use the utilities in the bios right before u flash it it will give you option weather wanna keep the bios dma or delete it,if you keep it this is wat happen but no harm done,yea like yehlai said rules of flashing...revert back everything to original bios setting not the oc setting...it will give you problem...but for me asus is much more smart mobo since you dont have to reset cmos the old way just shut the power down and wait few minutes then it will reset itself,for gigabyte open the casing and reset the cmos....anyway wen you get it from rma,this wat happen to me la,i install everything back then the problem is still there...i reset c mos then only it boot up properly....

same problem.. i kick it
and it works find again