How can I check if my CPU is AMD64 compatible?

To find information about your CPU including architecture, execute lscpu in terminal.

Example:

lscpu

yields ...

Architecture:          i686
CPU op-mode(s):        32-bit, 64-bit
Byte Order:            Little Endian
CPU(s):                4
On-line CPU(s) list:   0-3
Thread(s) per core:    2
Core(s) per socket:    2
Socket(s):             1
Vendor ID:             GenuineIntel
CPU family:            6
Model:                 42
Stepping:              7
CPU MHz:               2301.000
BogoMIPS:              4589.37
Virtualization:        VT-x
L1d cache:             32K
L1i cache:             32K
L2 cache:              256K
L3 cache:              3072K

For Intel systems, the Vendor ID is - GenuineIntel and for AMD - AuthenticAMD.

But they are compatible. It is a bit of an historical artifact in that AMD was the creator of the 64 bit 'long' mode, and later Intel matched that creation.
But naming often refers to any 64 bit binary as an AMD/64bit format, usually with the label 'AMD64'.

Acer Aspire 5745G-724G50MNKS is 64 bit so you can run the amd64 download on it. I use the serial number (7545G) to google it and try to find items that included the architecture. Shops sell it with Windows 64 installed.

You will run into problems: looks like it is not 100% compatible with Ubuntu since I also found a bug report on this machine. It has amd64 stated as architecture so you can use amd64 on this.

This is a more general but very practical answer to questions like this. We assume that we have no idea on what hardware we are, and we do not want to know anything about processors or achitecture of our system.

• 32-bit processors are rare nowadays
• Therefore download the am64 64-bit iso of Ubuntu and create a USB or CD boot medium
• Boot with this and choose "Try out Ubuntu"

If that is a success and you are able to try out Ubuntu on your machine you then know for sure that your CPU is capable of running 64-bit Ubuntu. In addition you will also know that other hardware you may have is compatible. An installation will then be a success. If it fails go ahead with the 32-bit version.