7 beeps problem after CPU upgrade

Hello community,

I have a Dell Inspiron 5520 notebook having an i5 3210m CPU and a motherboard with HM77 chipset. My bios version is A14. 

I searched a list of compatible CPU products with the HM77 chipset and i found the link below. I see that my chipset is compatible with an i7 3612QM CPU.

https://ark.intel.com/content/www/us/en/ark/products/64339/mobile-intel-hm77-express-chipset.html?wapkw=intel%20hm77

Another link is given below in which my CPU and i7 3612QM was given in the same list of compatible CPUs. These two CPUs have the same sochet types.

https://www.dell.com/community/Laptops-General-Read-Only/Which-processors-are-compatible-with-a-my-dell-inspiron-15r-5520/td-p/4576061

So, i decided to upgrade my CPU with an i7 3612qm. I found an used one and i contacted with the seller to confirm that it has no issue. The seller said he already tested that it works well and have no problem. Then, i got this CPU.

I replaced my i5 3210m CPU to i7 3612qm with a quality thermal paste. But, the notebook does not start. I am completely disappointed. Any time i push the start button, 7 beeps are coming and bios screen does not appear as well as the windows screen. I searched this error code, i found that this points out a CPU or motherboard failure. Then, i changed my CPU back to the i5 3210m, 7 beeps disappear and everythink is working well. This means that my motherboard is working well with my i5 3210m CPU.

Can anybody please help me to fix this problem if it is possible? Is there any way to use this i7 3612qm CPU i already purchased, or it has a fatal trouble? Is my bios version is responsible to this failure or it is irrelevant.

Thank you in advanced.