4GB Trials and Tribulations

[PAGETITLE=Introduction] It wasn't too long ago that having 1GB worth of total system memory was more than enough for anything you wanted to do. In fact, the majority of people still use 1GB or less, and are content. When a few games were released though, such as FEAR and Battlefield II, people started to see clear benefits of moving up to 2GB worth of ram in their system. Those two games specifically can stress all areas of your system, including GPU, CPU and of course your system memory. This article is not a review of any 4GB kit, but rather an article explaining the pros and cons of moving up to 4GB. I have spent a lot of time overclocking both DDR1 and DDR2 4GB configurations, so you can expect in-depth performance reports later. Generally speaking, the better the graphics and higher the resolution a game has, the harder it will be on your ram. I found this out last year when I was conducting tests with the FEAR demo. I found, that simply going from 1GB to 2GB released a lot of stress overall on the system, and gave me far better overall FPS. The same results were found about Battlefield II, but I never personally performed any such tests. While many people are still using 1GB kits in their PC's, 2GB's are catching on at a very rapid pace. Speaking with one enthusiast memory manufacturer recently, they told me that they now sell *more* 2GB kits than anything else, so the transition is really in full effect. Of course, even with an Ultra High-End system consisting of a top end CPU and Quad-SLi doesn't really need anything more than 2GB. There just isn't a need for it, if you are focusing on one application at a time, such as a game. There's a certain mystique that some people have about having 4GB worth of ram in their computer. No doubt, there are indeed actual needs for this much memory, but most of these reasons usually have to do with multimedia production. Graphic designers, movie editors and even large Photoshop projects can hog all of your memory, and cry for more. There are also countless myths, or misunderstanding when it comes to having 4GB in your computer. The first is the fact that the more memory you have in your computer, the slower it will be, in terms of bandwidth. In fact, this is both true and false, depending on your motherboard and CPU configuration. We'll get into that shortly. One of the most popular myths is that Windows cannot physically see anything above 3GB. Again, this is also true and false. Due to technical 'limitations' or 'fixes' in Windows XP Home and Professional, the Service Pack 2 removed the ability for Windows to see a full 4GB. If you have Windows XP Home/Professional with SP1 still installed, then you should have no issues in seeing the full 4GB. If you have a current install of Windows x64 Professional of Windows Server 2003, then you will see the full 4GB regardless, even with the latest service pack. If for some reason you still don't see 4GB in Windows, it may be due to your motherboard or an option in your BIOS, such as PCI MMIO. So the ultimate fact is, if you want to see a full 4GB in Windows, you will need either Windows x64 Professional or a standard copy of Home/Professional that has not been updated to SP2. You could also use Server 2003, if that's the version you prefer. [PAGEBREAK] [PAGETITLE=4GB Technical Limitations] Depending on your system, especially your motherboard and CPU, upgrading to 4GB of system memory could be slower, or just as fast as 2GB. Throughout the article, we are considering 4GB to be (4) 1GB modules, or 4 * 1GB. While 2 * 2GB modules exist, they are scarce, expensive, and slow. 2GB modules are best suited for servers, because most are buffered, which is why they are so expensive. The performance increase or decrease will depend on whether you have an AMD or Intel. For my benchmarking tests, I will be using 4 sticks of PC2-6400 memory and 4 sticks of PC-3500 memory. Now that AMD AM2 has finally dropped, the DDR2 portion of the performance results may prove most interesting, since both the Intel DDR2 and AMD DDR2 are rather similar. One thing to bare in mind, is that as soon as you go from 2 * 1GB to 4 * 1GB, you are in effect going from 1T to 2T timings, which are latency related. 2T could prove up to 20% slower than 1T, which is why many systems will indeed suffer memory bandwidth/latency slowdowns, especially in synthetic benchmarks. That's where 2 * 2GB will be beneficial, because even though it's still 4GB, it should still able to handle the 1T timings. I won't get into how 1T and 2T timings work, because that would be an entirely separate article. To put it simply though, 1T is harder on the motherboard and memory controller, so having a 4 * 1GB configuration at 1T timings is far too taxing for any current motherboard and CPU at higher MHz, regardless of how high end it is. If you wanted to decrease the memory speeds so far in order to hit 1T with 4 1GB sticks, you may as well haul your 386 PC out of the closet. Simply put, if you have an AMD and are going to 4 * 1GB, you will experience slower speeds than you would sticking to a 2 * 1GB configuration. With Intel's, it could be either way. If you are using an nForce 4 Chipset, meaning you can do SLi on your Intel, then you will be taking the same route as DDR1 on the AMD. The nF4 Intel chipset allows you to use 1T timings for a 2 * 1GB configuration, and 2T for 4 * 1GB, so you will again experience slowdown with the latter config. If you happen to have an Intel chipset instead, such as the one on my ASUS P5WD2-E, then you will be using 2T regardless of what your configuration is. This is one reason why DDR2 seems slower in some cases than DDR1 when compared, because even a 2 * 1GB config on an Intel chipset uses 2T. Why this is the case, I have no idea. What this does in turn mean though, that moving to 4 * 1GB on the same chipset will keep the 2T timings, so the performance decrease should prove minimal... if any. To sum this up in simple terms: AMD - 2 * 1GB will always be faster than 4 * 1GB. AMD - On an AM2 nF5 chipset, 2 * 1GB will always be faster than 4 * 1GB. Intel - On an nForce 4 chipset, 2 * 1GB will always be faster than 4 * 1GB. Intel - On an Intel chipset, 2 * 1GB will be equal performance to 4 * 1GB. Note, that the descriptions above also apply for things that don't use all a full 2GB. On an extra note though, even if your PC can handle DDR2 memory at 1T, chances are you will not be able to retain that 1T timing above DDR2-800 speeds. At that point, the strain is becoming increasingly painful on your memory controller. Therefore, for either a 2 * 1GB or 4 * 1GB configuration with faster than DDR2-800 speeds, the performance should not change at all. As mentioned earlier, this is where people will actually benefit from having (2) 2GB modules, because they will retain 1T timings. The primary reason why this is not good for the average consumer, is because they are slower. I believe they max out at PC3200 speeds, and many come in ECC flavor, but not all. This means you could expect to pay an upwards of $800US for an low speed 4GB kit. Without a doubt though, engineers are working hard to produce chips for 2GB modules that don't suffer from a huge lack of speed that the current ones do. Ryan Peterson, CEO of OCZ Technology, was recently quoted as saying that they would be releasing 4GB kits consisting of 2 * 2GB, later in the year. The expected launch will be shortly before Vista, because that OS will prove to be system intensive. Considering Vista can take an upwards of 500MB of your ram on a fresh boot, that leaves you 1.5GB for your other app's and a high end game. Not exactly that much breathing room, depending on what you are trying to do. As soon at these 4GB kits are available, chances are that they will be superior to the speeds we are seeing from current 4GB kits. I am doubtful we will see the ultra high-end speeds that we do right now, but I believe 2 * 2GB kits with PC4000 and PC2-6400 speeds should be very possible. [PAGEBREAK] [PAGETITLE=General OC'ing with 4GB] Most computer enthusiasts enjoy knowing their computers are running at the fastest speed possible. This of course means overclocking the CPU, GPU and memory is on the top of their lists. The question is, is overclocking 4 * 1GB the same as 2 * 1GB? The answer is, yes and no. There have been a lot of yes and no answers today :) Overclocking the memory with each configuration is exactly the same, the process at least. But, say for instance you have a DDR500 2 * 1GB kit, that easily overclocks to DDR550 speeds. Can you expect to have the same DDR550 speeds in a 4 * 1GB configuration? This again depends entirely on the modules, and your memory controller. Your motherboard can play a huge role also, though. The first problem is whether the memory controller can handle overclocking four modules at once. Simply, it may prove to be too much strain, so you could be forced with stock speeds. You will have better success with a higher quality motherboard and CPU, but still nothing is guaranteed. The problem is harder if you want to overclock two different types of memory. For instance, there are some out there who may currently have a 2 * 1GB kit in their computer, and find another kit on eBay for a great price, so they snatch it up. If all four modules are *identical*, then your chances of a decent or good overclock are great, as long as your memory controller can keep up. If you have two different 2GB kits though, the chances of a good overclock are around 25%. First thing to take into consideration, is that two different kits of memory may have completely different chips. One may use Infineon, the other Micron. Because of the differences, your overclock probability is not as great as if the chips were all the same. Let's take another example... you have two separate kits that both use Micron 5b F chips, but one kit is by OCZ and the other Corsair. This is completely a random analogy, because...

4GB Trials and Tribulations

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Rob Williams