2GB vs. 3GB vs. 6GB

Less may not be more, but is it just enough?

You can never have enough money, ammo, or RAM. But is that really true? To find out, we looked at three very common memory configurations a person would face when building a new Core i7 machine. The first config is the upgrader. This person adopted DDR3 in the Core 2 days, and after paying $500 for 2GB of DDR3/1333 RAM, he sure as hell is going to migrate it to his Core i7 box, even if it means running the RAM in dual-channel.

The second configuration is the person who wants to scrimp a bit on RAM to perhaps buy a larger hard drive, so he buys 3GB of DDR3/1333. The third configuration is the geek who, sick of never getting more than 3.25GB of RAM in Windows XP, wants to break that 32-bit barrier. So he outfits his new Windows Vista Home Premium 64-bit machine with 6GB of DDR3/1333 RAM—and he damn well better see it say 6GB of RAM in the device manager!

Who has the optimum setup in terms of memory? Let’s find out.

The Test

For our test, we again reached for our MSI X58 Eclipse SLI board and first outfitted it with two 1GB sticks of OCZ DDR3 RAM to simulate our Core 2 Quad upgrader. The second configuration used three 1GB sticks of CSX Diablo DDR3 RAM. The third configuration used three 2GB sticks of Corsair Dominator DDR3 RAM. The Diablo RAM is rated for DDR3/2000 (although we could never boot our board at that speed with it), and the Corsair RAM is rated for 1600. We ran all three scenarios at DDR3/1333 speeds.

Again, we outfitted our X58 Eclipse SLI board with a 3.2GHz Core i7 Extreme Edition, an EVGA GeForce GTX 280 GPU, an Intel X25-M SSD, and Windows Vista Home Premium in 64-bit mode. We reached for the same combination of synthetic memory benchmarks, application, and gaming tests that we used in our other two challenges. Because we suspected that our standard benchmarks would not be enough to stress the amount of main memory, we also ran additional tests that would simulate a heavily loaded multitasking machine. The first was to launch Premiere Pro CS3 and open an HDV editing project. We then launched Photoshop CS3 and opened a 600MB PSD file. We also ran our Valve Particle Gaming test, which simulates multicore particle workloads. And we created an uber-workload by launching Premiere Pro CS3 and opening 30 images in Photoshop CS3, then running either Crysis or PCMark Vantage in 64-bit mode.

The Results

We saw fairly minimal differences between the dual-channel 2GB configuration and our 3GB and 6GB configuration in 3DMark Vantage and PCMark Vantage. Likewise, Valve’s Particle Test, Quake 4, and ProShow Producer performed the same regardless of memory amount. Everest Ultimate also showed very little difference among the three configurations, which was a bit surprising, since we’ve seen a difference between dual-channel and tri-channel in this benchmark in the past. SiSoft Sandra’s results, however, saw the tri-channel configs showing additional bandwidth. Again, we didn’t expect much of a difference with our standard tests, which ran fine with 2GB of RAM in dual-channel mode. We did, however, see
pretty good gains in our Photoshop CS3 test and Premiere Pro CS3 tests. Both handily favored the 6GB configuration over the 2GB and 3GB builds. We also saw minor improvements in ProShow Producer and MainConcept Reference.

Having 6GB of RAM will yield the best overall performance, but we were surprised by how well 2GB and 3GB did.

OK, so what about our tests designed to specifically stress big memory holes? That’s where we were first thrown for a loop. With Premiere Pro CS3 and Photoshop eating up a chunk of RAM, running our Valve Particle Test showed absolutely no difference. Why? We believe that all three apps were still below the 2GB threshold. That’s where we expected Crysis to make a big difference. With Premiere running and 30 large images open in Photoshop, surely we’d see a frame rate drop in this monster of a game, right? Nope.

Crysis is said to need 4GB of RAM to run smoothly, but the benchmark spit out the same frame rate with 2GB, 3GB, and 6GB installed. What gives? We suspect this is the result of one of the things Microsoft did right with Vista. The OS is far more efficient at memory management, and it likely just pushes aside applications to make room as needed. Performance was likely ameliorated by our use of Intel’s superfast X25-M SSD. This drive’s 200MB/s-plus read speed and zero access time is quite capable of masking disk caching that would be more apparent with a slower drive. We have to note that although the benchmark frame rates are fine, actual gameplay would probably suffer with these apps open—level loads would be slower, given that the OS simply has less RAM to play with.

PC Mark Vantage combined with Premiere and Photoshop actually gave us the results that we expected and in our opinion is a more reliable predictor of heavy memory loads. Unlike a gaming benchmark that’s fairly small and runs for only a few seconds, this application simulates application performance and tries to measure how well a system runs. For example, in one section, the app plays a sample of HD footage and measures the frame rate. We could visibly see PC Mark Vantage struggle at times to complete runs with the other application open, and even the video playback would stutter with the 2GB and 3GB configurations. It was only at 6GB that we saw acceptable performance with PC Mark Vantage.

Our take-away: You can actually get by with less amounts of RAM if you are a single-tasking kind of person. Even the 2GB, dual-channel combos yielded acceptable performance. We don’t recommend it though. The minimum a Vista 64-bit PC should run is 3GB and the recommended is 6GB. We say this because today’s CPUs are designed to have multitasking workloads thrown at them. With so many available threads, you’re expected to run multiple applications without significant performance slowdowns. By not having enough RAM, you hurt the machine’s multitasking capability and you won’t work as efficiently. 

 Next: RAM tips for buildling your new PC