First some info about my system:

Rig: I7 920, 6GB corsair dominator, Evga X58 mobo, Evga gtx295, sound blaster x-fi, 2x64GB ssd in raid 0, seagate 500gb hd.

Liquid Cooling system loop:

Resivor-->Pump-->2x80mm radiator-->CPU-->NB/SB-->3x120mm radiator-->Video card-->Resivor

cpu/gpu waterblocks are EK and my NB/SB is bitspower. im using 1/2" ID hosing with anti-kink coils. My pump is a D5 made by swifttech.

My question is why my CPU is overheating at idle speeds. Sitting in my bios after 5min. my cpu temp is at 83C. I checked my waterblock even and its on there secure.

For awhile i thought my pump was bad, which it could be, but is it possible that my nb/sb waterblock is bottlenecking/restricting flow?

Did you bleed the system? There could be a stubborn bubble trapped in there somewhere. Tilt and rock the system back and fourth to see if any bubbles are freed. 1/2 ID is on the larger side for coolant lines anyway, so the flow is going to be a bit slower opposed to 1/4 or 3/8. Which coolant are you using and did you remember to mix with distilled water? Also, make sure the thermal is making a good bond between the CPU block and core of the CPU.

First off if you have 2 radiators you should have been making two seperate loops. I'm not suprised you're having issues, how can the liquid flow like it should with all that head pressure. You have way too much in one loop imo. If you dont want your flow rates to decrease because of all your blocks and the rads, get an aftermarket flow nozzle for the pump.