Problems installing windows 7 64 bit on compatible system.

Okay so my problem lies in the installation of windows 7 ultimate 64 bit on my system.

Specs:

Intel i7 2700k processor
Intel DZ77BH-55k motherboard
Intel 180gb SSD
8gb memory

(feel as though this is all the necessary specs for my issue)

Problem:
I custom built this computer and after using the installation disk that contains both 32 and 64 bit. On my brother's computer we used this disk and it automatically installed to 64 bit without making us choose. However on my machine, it automatically goes to 32 bit even though all the parts are 64 bit compatible. My question is simply how can I install 64 bit windows 7 to utilize all 8 gb of memory. I have tried reinstalling i using the disk multiple times, each time giving me the 32 bit system.

TL;DR:
Basically tried installing windows 7 64 bit, however keeps giving me 32 bit system even though all components are 64 bit compatible. Used this disk on other computer and it booted up as 64 bit. How do I get my system to 64 bit windows 7.

Any response is greatly appreciated, Thanks.

Where did you get this DVD? How is it being activated?

Use the latest official 64 bit installer for your licensed version from Clean Reinstall - Factory OEM Windows 7. Those steps will also assure you get and keep a perfect install, even for retail.

I got this disk from msdm and I installed the disk for the other machines and it worked fine while doing a clean install from scratch did nothing for my machine.

I activated it using normal activation processes using the activation code.

Will try your solution if i cannot find an answer to this issue.

Edit: btw this is a custom build machine fyi.

I don't mess with 32/64 AIO disks which can malfunction in several ways. The latest official installers are available in both bit-versions and can have all OS versions unlocked using eicfg removal tool.

after using the installation disk that contains both 32 and 64 bit.

I got this disk from msdm

No, you did not, as MS do not make one.