Tuesday, October 28, 2008

memory for pc

Computer Power User Article - DDR Deathmatch
DDR Deathmatch
A Collection Of Kits Duke It Out For Memory Supremacy
There's no doubt about it—DDR2 is the most prolific system memory technology currently in use. All of AMD’s platforms rely on it, because the Phenom and Athlon processors all have integrated memory controllers able to recognize DDR2 modules exclusively. And although Intel is pushing the advantages of DDR3 memory, most third-party motherboard vendors are still arming Core 2-based platforms with DDR2 slots. After all, DDR2 is the incumbent. It’s significantly less expensive and, thus far, almost every bit as fast as DDR3.

But the undisputed reign of DDR2 is coming to an end, just like DDR before it. The imminent launch of Intel’s Nehalem architecture will not only see the X58 chipset embrace three channels of memory in lieu of two, adding extra throughput, but it will also support DDR3 alone. Officially, you should only expect Intel to advocate DDR3-1066. Behind closed doors, however, it’s clear that a number of motherboard vendors will adopt speeds as high as 2,000MHz to push performance even further.

AMD is also expected to hop onboard with DDR3, though it won’t be cutting ties with DDR2 entirely. According to the company’s internal roadmaps, AMD plans to launch its Socket AM3 interface at the end of 2008, simultaneously introducing DDR3 and its 45nm Deneb quad-core Phenom. Those AM3-based chips should drop into AM2+ motherboards, extending the life of systems using DDR2. However, you won’t be able to drop an AM2+ processor into one of the newer boards because the older Phenoms and Athlons don’t have DDR3 memory controllers built in.

And so, DDR2 and DDR3 will be your memory options through 2009, the former fading as the latter receives intensified backing from Intel, followed by AMD’s joining the party. By rounding up a handful of memory kits centering on both technologies, we seek to find the best options for overclocking, value, and overall performance.

Corsair TWIN2X4096-8500C5D

CPU Rating: 4

The first kit to hit our lab is Corsair’s verbosely named TWIN2X4096-8500C5D, a 4GB package consisting of two 2GB memory modules. Rated for DDR2-1066 frequencies, an enthusiast kit like this is ideal if you’re building a new system using an AMD Phenom X3 or X4 processor, which officially caps out at 1,066MHz.

Of course, raw frequency is just one variable in the performance picture. Corsair also emphasizes the low latencies of its Dominator family, to which the TWIN2X4096 belongs. At 2.1V, Corsair says that the 1,066MHz modules can achieve timings of 5-5-5-15-2T. Bear in mind that JEDEC, the semiconductor engineering standardization body responsible for defining DDR2, originally only went up to DDR2-800 in its list of DDR2 speeds. DDR2-1066 was added after the fact as a specialty spec late in 2007. Nevertheless, it bears the same 1.8V recommendation, so these Corsair modules are running a little “hot” vs. the official sanction.

Corsair deals with the higher voltage (and the increased heat generated as a result) by sandwiching the ICs on both sides of its PCB with thin extruded aluminum heatsinks. If you take a top-down look at the modules, you’ll actually see four rows of fins. The outer pair draws heat from the memory chips themselves, while the inner two pull heat from the circuit board.

If you’re building a Phenom-based enthusiast-class machine, modules like Corsair’s TWIN2X4096-8500C5D are ideal for several reasons. First, they take advantage of the fastest speed grade recognized by AMD’s built-in controller. Second, they sport ultra-low timings—a one-two punch for realizing great performance. An unlocked Phenom Black Edition CPU on a 790FX/SB750-based motherboard is going to yield the best overclocking results without ever needing to get involved with extreme memory tweaking.

But ironically, in order to get the most comparable benchmark scores, we shied away from the Phenom/790FX combo and tested using Asus’ 780i-based Striker II Formula motherboard armed with the same Core 2 Duo E8500 used to evaluate the other five kits. Corsair’s Dominator kit had little trouble keeping up with and, in the case of our Photoshop test, beating the DDR3 contenders. Of course, the extra burst of speed comes from running 4GB of capacity. We’re at an inflection point now where the move to 4GB does outweigh an extra bit of frequency.

Crucial 2GB Ballistix DDR2-800 (BL2KIT12864AA80A)

2GB (1GBx2)
Ballistix DDR2-800
Rating: 3.5

You don’t always need to spend big money to garner great performance. Priced under $60, this 2GB Crucial Ballistix memory kit centers on DDR2 technology rated for 800MHz. We heard great things about its overclocking headroom, though, and wanted to see how far these modules would go. But before we tune the 1GB sticks, it’s worth noting that even at stock settings, Crucial’s kit puts up a respectable fight. It is officially rated at 800MHz, running aggressive 4-4-4-12 latencies. Matched to an older, pre-Phenom AMD processor with a memory controller limited to 800MHz, these modules make for a perfect drop-in.

The Ballistix modules use nearly as much voltage as Corsair’s Dominator family—a whopping 2.0V. Like Corsair, Crucial employs heat spreaders to help combat the effects of pumping more juice through the modules. The orange aluminum plates don’t quite cover all of the memory ICs, but that doesn’t seem to hurt their performance at all. And despite overshooting JEDEC’s 1.8V standard by 0.2V, Crucial’s offering handles heat without an issue. But just in case these modules succumb to electromigration due to the elevated voltage, Crucial also protects the 2GB kit with a lifetime warranty; you’re covered.

Crucial’s kit steps into this technological cage match at a disadvantage. It not only centers on aging DDR2 but also runs at just 800MHz and offers 2GB of capacity as a kit. Although memory bandwidth at default settings clearly lags, overall performance remains competitive—even beating the 2GHz DDR3 kit from OCZ priced nearly $200 higher. Best of all, we saw great overclocking performance from the Ballistix modules. Hitting 1,066MHz at CAS 4 was stable; bandwidth started to drop off at 1,083MHz at CAS 5.

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