Memory Capacity And Data Rate
Memory Speed
Intel's entry-level chips are limited to DDR3-1066 memory speeds. As long as you're looking at kits rated for less than 1.65 V, we recommend arming the Pentium and Celeron configurations with the cheapest modules that you trust.
AMD’s APUs are compatible with kits running at up to DDR3-1866. The reason they accommodate more aggressive data rates is to provide the on-die graphics engine with plenty of memory bandwidth. Consequently, it's more important to choose the right speed, and potentially spend a little more money on higher-end modules.
| Header Cell - Column 0 | 4 GB (2 x 2 GB) | 8 GB (2 x 4 GB) |
|---|---|---|
| DDR3-1066 | $25 | $42 |
| DDR3-1333 | $22 | $39 |
| DDR3-1600 | $27 | $41 |
| DDR3-1866 | $34 | $55 |
Memory Capacity
The next important question to answer is how much memory should you buy? Motherboards in our price range typically feature a pair of slots, leaving us to choose between 4 GB (2 x 2 GB) or 8 GB (2 x 4 GB). We decided to use modules with the highest latencies, since they're cheaper. Seeking out low-latency DDR3-1866 kits, in particular, can become an expensive task.
Our benchmarks demonstrate large jumps in performance from 1066 to 1333 MT/s, as well as 1333 and 1600 MT/s on AMD’s APUs. The difference between 1600 and 1866 MT/s is much smaller in our productivity-oriented tests, though, and we've seen the jump to 1866 MT/s doesn't have as large of an impact in gaming as using DDR3-1600. Our recommendation would be to spend whatever it takes to complement an APU with DDR3-1600. Stepping up to DDR3-1866 does help games like Metro 2033. But for lighter titles, such as DiRT 3, the difference is in the low single-digit percent range.
We also see that 8 GB (2 x 4 GB) is slightly slower than 4 GB (2 x 2 GB) at identical frequencies and latencies using our AMD-based platform for productivity-oriented tasks. The opposite proves true in the gaming-based results. Once the graphics engine starts monopolizing system member, it pays to have more capacity. We also see that it's better to have 8 GB using the machine built on Intel's technology.
Bottom Line
There's a quantifiable benefit to using 8 GB of system memory, but the performance garnered with 4 GB installed is just fine, too. Generally, the need for 8 GB of RAM in an entry-level system like ours is questionable, so we recommend sticking to 4 GB, at least when you're trying to get in for as little money as possible. Memory can be upgraded later if you think ahead and buy a motherboard with four DIMM slots.
In fact, you can use some of the money you save on a 4 GB kit to buy higher data rates, though we'd suggest not spending more than an extra $10 to step up from 1600 to 1866 MT/s modules.
