DDR3 memory: late 2008

Late in 2008, the situation on the market of memory has changed radically. First, that is seen from the serious drop of prices for DDR3 memory modules. Secondly, DDR3 memory modules with the rated frequency 1600 MHz have appeared in wide assortment. However, only a minor part of buyers will be able using the advantages of such memory. In particular, if the beginner use buys a DDR3-1600 kit, he is unlikely to benefit from such fast memory. Let me explain why. Normally, motherboards set the operation mode for modules like DDR3-1333 and as a result the performance of memory subsystem in most applications will be at the same level as that for DDR2-800 or DDR2-1066 memory. And at the price, the DDR2 memory is much cheaper. Of course, you can enter the BIOS and manually set the required frequency. But the user with this skill level is unlikely to be referred to as a beginner user. If the user knows deep enough about the motherboard settings, he can reduce the CPU multiplier and raise the FSB speed to 400 MHz (for motherboards aimed at the Intel platform). In the end, the CPU will run at about the nominal frequency, but the overall system performance (FSB 1600 MHz QPB, DDR3-1600 memory) will be much higher. The beginner user can't get access to this configuration, since widely advertized Intel's processors with the nominal FSB equal to 400 MHz (1600 MHz QPB) are missing at retail stores.

The second category of users for the DDR3-1600 memory are those enthusiasts who raise the FSB speeds in the CPUs to somewhere over 500 MHz. Currently, it is no longer a problem to make DDR2-1000 MHz memory needed for such configuration available. But with the serious overclocking (up to FSB~ 550-600 MHz) the requirements to the DDR2 memory specifications rise so essentially that it is more advantageous to use DDR3. It is indeed somehow more expensive, but it has no restrictions in the required frequency range. For instance, in the synchronous mode, the DDR3-1333 allows setting the FSB=667 MHz, while DDR3-1600 - FSB=800 MHz!

Lastly, the third group of users of DDR3 memory are professionals who work with some dedicated software. If the speed of this software directly depends on the memory bandwidth, and DDR3 with the frequencies 1333 MHz or 1600 MHz gives a real advantage in speed, then such users immediately migrate to DDR3-1600 once it is available.

In our today's review, we'll be testing all the DDR3 memory kits available at our test lab. We start with the A-Data AD31600X001GU modules.

A-Data AD31600X001GU

The package of the modules is the nicest and most impressive we have ever seen.

The exterior of the modules is on par with the box:

The sticker on the package and on the modules contains information on the nominal frequency, operating voltage ranges, and the latency timings.

We now move on to the tests and look at the SPD data:

So, the SPD reports that for the nominal voltage 1.5V the maximum (stable) frequency of the module equals DDR3-1333 MHz. Indeed, our attempts to start up the modules at DDR3-1600 with Vmem=1.5 did not succeed. Therefore, the user needs to set the recommended memory voltage range (which is in fact an overclocking sanctioned by the manufacturer). At Vmem = 1.75V, the A-Data memory ran at DDR3-1600 and at quite good latency timings:

Moreover, we were able to push down the latency timings to 7-7-7-20 without any loss in the system stability.

As regards the overclocking capability of A-Data AD31600X001GU modules, it is relatively low: the maximum frequency is DDR3-1800 MHz at 1.85V.

Two Samsung memory modules

We are now examining another pair of DDR3 modules, this time one made by Samsung.

In our tests, they are not taken into account because they are not paired (one - 1 GB, the other is 2 GB), while the other kits are paired and worked in the dual-channel mode.

On both the brackets, similar chips were installed:

The original information can be found from the stickers:

As the stickers say, the memory meets the PC3-8500 standard or, in other words, the rated frequency equals DDR3-1066 MHz.

Here is the notation for the DDR3 indices:

From the SPD information, we know that the 1 GB memory module by Samsung is able running at DDR3-1220 MHz with the latency timings 8-9-9-23 at the rated voltage.

As regards the overclocking, at the rated voltage the memory module was able to cope with the frequency DDR3-1600 MHz. However, all that became possible due to the substantial increase in the latency timings.

However, if we raise the voltage Vmem to 1.7V, it is possible to push down the operating latency timings to quite reasonable levels (8-8-8-20).

Then we tested the 2GB memory module by Samsung whose specifications proved to be fully identical.

Finally, we tested a system with two "mixed" Samsung modules and found no deterioration in the results. In particular, with the Vmem raised to 1.8 V the memory ran at DDR2-1800:

Besides, at Vmem=1.7V it became possible to push down the latency timings to 8-8-8-20.

Qimonda PC3-8500

We now move on to Qimonda PC3-8500 memory modules which arrived at our test lab immediately after the emergence of the DDR3 memory standard.

Each module is of 1GB capacity, and the memory chips are made by Qimonda:

Sticker on the module:

SPD information:

As you can see, the declared frequencies and latency timings fully match the parameters of Samsung modules. However, the overclocking capability of Qimonda modules proved to be somehow different. In particular, at the rated voltage (Vmem=1.5V) the maximum stable frequency was DDR3-1333 MHz (with a small margin).

Then, if the user is not afraid of raising the Vmem to 1.8V, he can increase the memory subsystem performance through raising the frequency to DDR3-1400 MHz:

or through pushing down the latency timings to 8-8-8-20:

In this case, the most effective way is the reduction of latency timings since the frequency margin in Qimonda modules is not high.

So, let's recap all the results in a table:

Test-bench configuration:

Final Words

Summing it all up, we note the following. For a year after the DDR3 memory appeared on sales, its specifications have gone up with the price gone down substantially. In particular, the retail price of a 1 GB Samsung PC3-8500 module is at about $45, whereas the price of a Samsung PC3-10600 module of the same capacity - at about $55. As it seems to us, all the entry modules by Samsung are manufactured from the same chips (similarly to DDR2 memory chips). So, unless assumed operating memory frequencies exceed DDR3-1600 MHz, we can buy cheaper modules with the rated frequencies DDR3-1066 or DDR3-1333 MHz. Due to the polished process technology, the overclocking capability of such modules is quite sufficient to attain the required frequency.

If the buyer has no financial restrictions and he needs modules of guaranteed operating frequency DDR3-1600 MHz, there is a vast choice. One of the options is a kit of 1GB A-Data AD31600X001GU modules which costs about twice as much (~$200). At the same time, the user will anyway have to resort to overclocking, namely, to raise voltage on the memory modules.

We should also keep it in mind that despite the memory manufacturer's guarantees and the guarantees of the motherboard manufacturer regarding the system operability at 1600 MHz, some combinations may not attain this frequency. In particular, in our test lab there are two or three motherboards at which the A-Data AD31600X001GU modules simply wouldn't work. Therefore, it is important to remember that each combination (motherboard revision + BIOS version + CPU stepping + memory modules) has its own overclocking capability which can't be determined precisely and is guaranteed by none.