thanks for the effort bro 
Iāll only be able to try on the weekends and will post the results later.
ok, i tried putting the RAM in different slots as mentioned in the manual but no use 
After putting the RAM in different slots, the BIOS stopped showing the fan speed and the processor temp was a bit higher than before.
So, i put up the RAMs as before and connected the 4-pin fan header to the 3-pin case out fan header on the motherboard. Now the fan speed was around 1500-1600 with idle temps of 50 degrees (as before).
Then i fired up Intel TAT and loaded the CPU, the temps rose to about 70 and fan speed rose to around 2600 rpm. So, the problem still persists i.e. inspite of using the connecting the fan to 3-pin header fan speed is not at 100% at all times and is controlled by PWM. Hereās tje pic:
http://www.imgx.org/pthumbs/small/7373/temp.JPG
Now, should i cut the 4th unused wire of the cpu fan header? will it serve any purpose as it is already unused bcoz i have connected it to the 3-pin header?
Can i connect my 4-pin cpu fan header directly to the power supply instead of the motherboard header?
If this doesnāt work, then iāll buy a 3-pin cpu heatsink fan whenever i visit Nehru Place.
You have some issue in the BIOS.
Your temps are all right for the stock cooler, btw, I have about 70 degrees with TAT on my E6600.
Cutting the 4th wire may help. On the 4-pin header, the output is always 12V, and the BIOS controls the fan speed through the PWM pin (pin 4). On 3-pin headers, the DC output changes with zone temperature and CPU temp, which is why youāre still speed-controlled.
so u mean that even when i am using the 4-pin cpu fan header on a 3-pin motherboard header, the 4-th PWM wire is still used. So, cutting it off should serve the purpose, isnāt it? and cutting it off shouldnāt cause any problems?
so u mean that even when i am using the 4-pin cpu fan header on a 3-pin motherboard header, the 4-th PWM wire is still used.
No. How can that be if the 4th pin of the connector is plugged to a 3pin mobo header?? Itāll b simply protruding out. In that case BIOS wont be controlling the speed although it reports the rpm.
So, cutting it off should serve the purpose, isnāt it? and cutting it off shouldnāt cause any problems?
U neednāt cut it off at all.
on mine, connecting the intel fan to a 3-pin header results in 2800rpm 
intelās mobos suckā¦ iāll buy a new heatsink fan once i go to NP.