As first test we ran the memory at 200 MHz, at the standard voltage of 1.8V, to see how it performs at everything set to stock. The next test determines the maximum overclocking at 1.8V, which is something you would experience if your motherboard does not allow memory voltage adjustments at all.
For the next three tests we raised voltage to 2.1V, 2.2V and 2.3V. As you can see there is no difference in maximum clock here.
In the next two tests we reduced memory timings to 3-3-2-4. The first test at CL3 allows you to compare performance of CL3 vs. CL4 (first test).
The last two tests are running at the maximum CPU and memory clock which is a real-world scenario. You want to maximize both CPU and memory speeds. The first test here is at memory 1:1 in sync to FSB, the second one uses the 3:4 multiplier. These two tests are to find out if and how much the Pentium 4 profits from running at higher memory speed than FSB. As you can see the gains are there, but not so big, except for the Everest Write Benchmark. Depending on the application you will see a 1%-3% performance increase.
During testing I realized that the i925XE's memory controller seems to become unstable in the 400 MHz memory range. I would expect that there is some more overclocking possible with this memory.
For further comparison, the test "JEDEC DDR2-400" shows a generic DDR module running at JEDEC standard timings.
OCZ EL DDR2 PC2-6400 Platinum XTC
CPU Clock & Memory Ratio
Memory Speed
Memory Timings
Everest Read
Everest Write
Everest Latency
Quake 3 Timedemo
3DMark 2001SE
SuperPi Mod 1M
15 x 200 1:1
200 MHz
4-5-4-15 1.8V
5228 MB/s
1524 MB/s
103.4 ns
284.2 fps
20900
45.08s
15 x 193 1:2
387 MHz
4-5-4-15 1.8V
5552 MB/s
2139 MB/s
81.9 ns
287.3 fps
20434
44.00s
15 x 200 1:2
400 MHz
4-5-4-15 2.1V
6029 MB/s
2324 MB/s
78.9 ns
292.9 fps
20958
42.69s
15 x 199 1:2
400 MHz
4-5-4-15 2.2V
5950 MB/s
2293 MB/s
79.4 ns
291.2 fps
20875
42.95s
15 x 198 1:2
400 MHz
4-5-4-15 2.3V
5952 MB/s
2294 MB/s
80.0 ns
290.1 fps
20769
43.13s
15 x 200 3:4
267 MHz
3-3-2-4 2.1V
5954 MB/s
2141 MB/s
88.2 ns
290.3 fps
20919
42.70s
15 x 216 3:4
288 MHz
3-3-2-4 2.1V
5954 MB/s
2141 MB/s
81.6 ns
313.7 fps
22168
39.53s
15 x 291 1:1
291 MHz
4-5-4-15 2.1V
7600 MB/s
2223 MB/s
71.0 ns
412.0 fps
27175
30.89s
15 x 291 3:4
388 MHz
4-5-4-15 2.1V
8127 MB/s
2691 MB/s
66.0 ns
417.9 fps
27692
30.06s
JEDEC DDR2-400
200 MHz
4-4-4-12 1.8V
5326 MB/s
1585 MB/s
102.0 ns
284.5 fps
20159
44.45s
For an easier comparison with other modules, we set a maximum voltage of 2.1V and tested until we found the highest clock frequency and fastest timings for this memory. The benchmarks Everest Read, Everest Write and Quake 3 were run. We then calculated the performance increase in percent compared to a generic DDR2-400 memory running at JEDEC DDR2-400 (4-4-4-12). The average percentage of the three benchmarks is listed in following table: