AMD Radeon™ R9 370 with 4GB GDDR5 vs HD 7870

Solution
They will perform basically the same unless the memory difference comes into account.

And besides that you could save around half the price by doing some work instead of getting a prebuilt Alienware system.

A system that doesn't has the smallest amout of lowest possible speed memory needed for todays gaming.
A system that features a RX460 instead of a R9 370
A system that has a power supply from a trustworthy brand.
A system with the same hard disk size AND an SSD.
A system with a nice case, a system that also includes Windows 10, a DVD writer and a wireless card.
A system with a CPU that will gime you more performance in games while still being less expensive.
A system with a proper cooler for the CPU.
They will perform basically the same unless the memory difference comes into account.

And besides that you could save around half the price by doing some work instead of getting a prebuilt Alienware system.

A system that doesn't has the smallest amout of lowest possible speed memory needed for todays gaming.
A system that features a RX460 instead of a R9 370
A system that has a power supply from a trustworthy brand.
A system with the same hard disk size AND an SSD.
A system with a nice case, a system that also includes Windows 10, a DVD writer and a wireless card.
A system with a CPU that will gime you more performance in games while still being less expensive.
A system with a proper cooler for the CPU.
 
Solution