After upgrading Lenovo 3000 N200 Intel T2330 to T9500 CPU Fan stays on High Always. Running a dual Boot with Windows XP & 7. Stays high on both never decreases & CPU not hot, why & how do I fix it? No other problems besides this.
Check the ENTIRE cooling system and see if something is wrong (or hot). There may be sensors installed that can't be accessed by temperature monitoring programs but are making an impact. Also note that the T9500's FSB is higher, so northbridge may be a suspect here (the Max TDP is same, so it's not CPU itself and as you said, it's cool).
Also it could be a BIOS issue. Maybe if it doesn't detect supported CPU, it automatically switches to fastest fan mode? If the BIOS isn't the newest, update it. Check if the T9500 is shipped as stock CPU on any versions of your computer.