Let us continue with the most important part of the test report, the highest possible stable performance. The multiplier adjustment remains on 13x with all frequencies, because an adjustment for the CPU in half multiplier steps would be too inaccurate to get nearly the same CPU frequency for all tests. Microsoft Windows 7 RC Ultimate Edition is used as the operating system. The stability was examined with the software Memtest86
and SiSoft Sandra Lite 2010c program is used for all benchmarks, since it offers extensive adjustments and a fast result comparison. BTW. the latest SiSoftware Sandra 2010c version is available on our download server and can be downloaded very fast. All benchmarks are also included in the free Sandra Lite version.
First the maximum possible frequency of the memory module was determined with default 1.50 Volt (1,53V). The memory frequency was increased in small steps with a fixed memory timing of 8-8-8-24 2T and default memory voltage, as long as the detailed memory test with Memtest86 runs without any errors. This quite long testing time ensured that this frequency works really stable with these modules.
The highest possible frequency with 8-8-8-24 2T (CAS-TRCD-TRP-TRAS) timings and 1.53V was 743 / 1486 MHz.
Here is a Snipping screenshot of CPU-Z 1.53 with 743 / 1486 MHz and 8-8-8-24 2T with 1.53 Volt:
Of course it’s possible to run much higher frequencies with increased voltages or lower timings, because the frequency values and timings depends directly from each other. But officially Crucial specify only a voltage of 1.50 Volt without loosing the warranty. The voltage should not be increased very much without further cooling modifications.
The benchmark comparison of all DDR3 memory modules were tested with the default 1.53 V, where these Crucial 8GB modules reached 1486 MHz. This highest possible clocking on the default DDR3 voltage was compared now with two other settings. On the one hand they were tested with 200 MHz reference clock x6,66 = 1333 MHz and SPD values (SPD values are programmed in the SPD IC by the manufacturer). On the other hand the highest possible frequency with the permitted manufacturers voltage was determined at 8-8-8-24 2T. But in case of these modules the highest voltage is identical with the lowest test voltage, so the second test is equal to the first result.
However, unofficially without bearing on the total evaluation these modules were also tested with somewhat more memory voltage. With 2.00 V maximally 752/1505 MHz could be achieved. However thereby the RAM temperature increased within a short time from approx. 38,4°C at 1486 MHz with 1.5V to approx. 51,6°C. That should be already a reason for a passive or active memory cooler, because this memory temperature was measured externally with an infrared thermometer. The internal temperature of the RAM chips is thus clearly over this value.
But let us now continue with the official test, where all modules are tested with nearly the same conditions to get a better comparison to the previous tested memory modules. With a frequency of approx. 667 MHz the SPD EEPROM autodetection timings were 9-12-12-30 2T (CAS-TRCD-TRP-TRAS).
Here is a Snipping screenshot of CPU-Z 1.53 with 666.7 / 1333 MHz and 9-12-12-30 2T:
Here are the SiSoftware Sandra 2010 benchmark results:
| Frequency | Timing | Memory Voltage | RAM Range Int Buff’d iSSE2 | Memory Bus Range | Memory Latency |
| 223 MHz * 6,66 = 1486 MHz | fix (8-8-8-24 2T) | 1.53 Volt | 13,12 GB/s | 23,22 GB/s | 78 ns |
| 223 MHz * 6,66 = 1486 MHz | fix (8-8-8-24 2T) | 1.53 Volt | 13,12 GB/s | 23,22 GB/s | 78 ns |
| 200 MHz * 6,66 = 1333 MHz | SPD (9-12-12-30 2T) | 1.53 Volt | 11,64 GB/s | 20,84 GB/s | 95 ns |
By the way, the “Memory Bus Range” is no benchmark value, but this value is quite simple to calculate by the frequency and this is useful for a benchmark comparison.
Here’s a diagram of the benchmark values:
Here is a direct benchmark result comparison of some DDR3, DDR2 and DDR memory modules:
Of course we can’t expect miracles without heatspreader and without further cooling one should not increase the voltage much over manufacturer data of 1.5 V, but the result is excellent for the JEDEC standard voltage. The two Crucial 4GB UDIMM PC3-10600 CL9 modules are with this result at 1.5 V memory voltage only a little bit below the 2GB DIMM PC3-10600 CL9 modules from Crucial and that is respectable.