did you take out the small battery on the back of the logic board after replacing the CPU? leave it out for a couple of minutes; Resets the RTC. SMC reset might work as well.

all MacBook Airs from 2010 onwards need the EXACT matched partnumber for the batteries. make sure you get the battery labeled as A1405. do NOT get the battery labeled as A1377 or anything that they say works with any other MacBook Air than the mid 2011 model. (some websites list the same batteries for the 2010 and 2011 models: this is not correct and they're incompatible). I have had these issues multiple times, had a freakin headache because suppliers kept sending me mismatched parts; always the same result: the MacBook Air freezes up and is using huge amounts of cpu on kernel task because of the mismatched battery. If you DID order the A1405, then you've probably got a DOA, and you need to send it back in for a swap.

the little black piece of plastic with adhesive on it, is just there to keep the camera/airport-cable in its place. The reason they added this, is that when you slightly misplace the connector whilst power is on the logicboard, the cable can cause a shortcircuit on the logic board. Look for the black piece of tape/sticker directly on the right side of the connector on the board. You can pry this sticker of with a nylon stick. Below it, there are several resistors/capacitors that may or may not have been blown: this is visible as a black-brownish burnt spot. if this is not the case there is a chance you can fix it by disconnecting the cable again (making sure all power to the board is removed!!) and, as suggested earlier, make sure the connector is placed exactly straight into its receiving end and make sure it's nice and snug (press it a little with the nylon stick, but not too much as to force the connector off the board) Otherwise you may have blown the airportcard inside the display clutch cover (less...

Hello everyone, since i hadnt gotten a reply soon enough, ive taken this iMac in to my supplier and tested it with a bunch of known-good-parts. I've swapped the LCD (twice), V-sync Cable, Inverter Board, LVDS cable, even all of these items. The vertical wavy noisy lines remained visible. After logically assessing that this cannot be the video-card (digital video artifacts or any other typical GPU related issue generally looks totally different, plus this has a sort of 'analogue-ish' look to it: the lines are like an old CRT-screen that has gone bad, or an old TV that's got bad reception on the coax cable) Ive concluded that it must be the Logicboard, and probably the LVDS connector on the board. I am pretty darn sure i havent ripped the cable out of the connector when opening up the iMac (i've opened up imacs at least a million times before and know what to watch out for) however, maybe this specific connector had already been played with before and gotten a little sensitive.. just thought i'd let you guys...