BMW Repair: Cooling system problems on a 99 E46 323i, blown head gasket, fan clutch

Question
i have yet to check if there is a blown head gasket however i have seen no tell tale signs of one so far ( coolant in the oil, smell from exhaust or coolant comming out the exhaust). as for the electrical fan it did come on first and well after a 30 min drive on the high way at about 85mph i checked if the mechanical fan clutch came on and it did .. i did notice that the electrical fan was coming on and off for about 20 seconds it would be on then shut off for about 2 - 5 seconds ( the AC was running ) driving the car at 85mph and a steady rpm (about 3500) didn't show any signs of leaking from the reservoir cap but once the rpm started climbing and i got up to about 120mph ( about 3am no traffic)  you could smell the coolant being blown out and when i checked it yet again no leaks from anywhere else except the reservoir cap
any suggestions?
-------------------------------------------
The text above is a follow-up to ...

-----Question-----
i recently changed ALL hoses, the resevoir, thermostat , waterpump and even the resevoir cap twice. well the problem i am having is coolant is being blown out from the resevoir cap still! usually happens when the car is being driven at high rpms about 5000 and up (when i step on the kickdown ). this started happening around july when i had to change the resevoir because it just split at one corner and leaked out all of the coolant then i noticed the hoses needed to be changed also so we changed those- its around the same time we changed the waterpump. there is NO leaks anywhere else other than form the resevoir cap. please what could have caused this i am stomped and out of ideas !
-----Answer-----
Donovan, Please have the head gasket checked for leaks chemically. Also is the Electric fan comming on and working? Is the mechanical fan clutch engaging when the engine gets really hot. You should feel a torrent of air all the way back at the windshield when the fan clutch finally engauges with the hood open. Run the engine at 3000-3500RPM with the hood open and see if the Fan clutch engauges. Electric fan should come on way before the fan clutch does. Also turning on the A/C will turn on the Electric fan. Where does the temperature gauge read? To me sounds most like a fan or lack of airflow problem, but make sure the cylinder head gasket isn't blown and leaking cylinder pressure into the cooling system pressurizing it.
-Evan

Answer
Donovan, my money would be on the Electric cooling fan. The fan needs to stay on consistanly when the engine is very warm or when the A/C is on. Don't feel bad that you replaced the other components because BMW worse downfall is the cooling system and all the plastic components. Where is the temp. gauge when the resevoir is boiling over?
-Evan