AnandTech: OCZ EL PC2-8000 XTC: Low Latency PLUS DDR2-1100

Stock Memory Performance

As discussed in earlier DDR2 memory reviews, the Intel platform does not really allow for easily testing different memory speeds at the same CPU speed. Instead most top motherboards provide a wide range of memory ratios that match available DDR2 memory. Most end-users can therefore select the memory ratio that matches their DDR2 memory speed. For those reasons, we first tested all of the stock ratios at the fastest stable timings we could achieve at the given ratio. With ratios, CPU speed remains the same at 3.46GHz in our memory test bed, and memory speed is varied by selecting different ratios.

OCZ EL PC2-8000 XTC (Stock Memory Ratios) - 2x1GB Double-Bank
CPU Ratio at 3.47 GHz	Memory Speed	Best Memory Timings (Voltage)	Far Cry (fps)	Sandra Unbuffered	Sandra Standard Buffered	SuperPi Mod 1.4 2M places (time in sec)	Half Life 2: Lost Coast (fps)
(4:3)	400 DDR2	3-2-2-6 1T 1.8V	61.5	INT 3001 FLT 3037	INT 5614 FLT 5608	87.6	75.6
(1:1)	533 DDR2	3-2-2-9 1T 2.1V	63.07	INT 3570 FLT 3600	INT 6500 FLT 6498	85.3	84.2
(4:5)	667 DDR2	3-2-3-10 1T 2.1V	63.07	INT 3999 FLT 3995	INT 6710 FLT 6691	84.7	83.4
(2:3)	800 DDR2	3-3-3-11 1T 2.1V	64.52	INT 4301 FLT 4356	INT 6774 FLT 6788	83 .3	81.7
(1:2)	1066 DDR2	4-4-5-14 1T 2.3V	64.38	INT 4576 FLT 4639	INT 6840 FLT 6843	82.1	81.2
*Rated Speed Overclocked 3:5 (300x13)	1000 DDR2*	4-3-4-12 1T 2.2V	64.75	INT 4982 FLT 5046	INT 7649 FLT 7654	72.9	95.2
Highest Performance Overclocked 3:5 (318x13)	1060 DDR2	4-3-4-14 1T 2.3V	75.06	INT 5260 FLT 5303	INT 8105 FLT 8107	69.1	96.7
Highest Mem Speed Overclocked 1:2 (275x13)	1100 DDR2	5-4-5-15 1T 2.35V	66.21	INT 4720 FLT 4785	INT 6952 FLT 6947	80.2	89.8

Since the OCZ PC2-8000 EL is rated at DDR2-1000, the 1000 speed was also tested. To achieve that speed the 889 memory speed was selected at the standard 1066 FSB (266 setting quad pumped). The FSB was then overclocked to 300 (1200 FSB) resulting in a memory speed of DDR2-1000. You can clearly see that the OCZ PC2-8000 EL performed much better than the rated timings of 4-4-5-15. Our testing found complete stability at DDR2-1000 at 4-3-4-12 timings.

In the introduction it was pointed out that the fastest possible timings with today's DDR2 are 3-2-2. If you look closely you will see the OCZ PC2-8000 works fine at the fastest timings that can be selected at both DDR2-400 and the 1:1 memory setting of DDR2-533. These are both the fastest timings we have ever been able to run with complete stability with DDR2. In fact all the way up to DDR2-1066 this new PC2-8000 memory sets new records for the lowest latencies we have found in testing DDR2 memory.

Despite the fact that CPU multipliers can not be dropped below 12X on the Intel platform, it is important to keep in mind that the first 5 table rows, from DDR2-400 to DDR2-1066, represent a constant CPU speed of 3.46GHz with memory running at faster speeds through ratios. 1:1 should always have the least overhead in the current Intel universe, but the DDR2 memory still scales well with speed over the full range. Memory bandwidth improves with memory speed, as does raw calculation performance. However, this does not always translate into linear gaming performance curves in Half Life 2: Lost Coast and Far Cry.

The PC2-8000 topped out at DDR2-1100, which is the fastest speed we have ever achieved with DDR2 memory. Timings were still a respectable 5-4-5-15. Performance was excellent at DDR2-1100, but it was not the fastest performance found in our testing. The distinction for fastest overall performance goes to the rated DDR2 speed of 1000. At that speed the CPU is running at 13x300 or a 1200FSB.

The memory at this speed is running a 3:5 ratio overclocked to 300 for a resulting DDR2-1000. At this speed memory timings are still a very aggressive 4-3-4-12 and this does influence the excellent memory performance we found in our benchmark suite.

While DDR2-1100 was within reach in our tests, memory timings of 5-4-5 were required for stability. We were able to achieve even higher performance at the fastest stable memory speed that could be achieved at 4-3-4 timings at a base 3:5 ratio (DDR2-889), This turned out to be DDR2-1060 at FSB of 1274. We included results for Highest Performance in the chart and used these highest performance settings in the charts for Best Performance (Highest Ratio). The system was 3D stable at 4-3-4 timings at DDR2-1067, and all benchmarks except SuperPi ran fine at 1067. SuperPi was unstable at settings above 1060 at 4-3-4 timings.

There are other possible approaches to overclocking DDR2 memory on the Intel platform. Probably the most logical, given the memory controller resides on the Intel chipset rather than the processor, is to look at overclocking at a 1:1 ratio. For our test setup that means a DDR2-533 base setting. You can see results of that approach on page 10.

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