Alienware Aurora R4 System Specifications >< What motherboard do I have?

E203413   is  Not a Dell Part Number DPN  it is a UL Fire safety regulatory marking for electronic circuit boards. The Backwards UR is Underwriters Lab Logo.

UL Standards 

https://www.intel.com/content/dam/support/us/en/documents/motherboards/desktop/e210882_information.pdf 

Alienware Aurora R3 i3 i5 i7 Main System Mother Board LGA1155 (46MHW DF1G9) for example is a DPN which may also have a QR code on it.