To check out the practical performance of our memory kit we put together a special testbed. Since the kit refused to work with the ASUS P5E3 Premium mainboard sample based on Intel X38 chipset we had at our disposal, the testbed was built around ASUS P5K3 Deluxe on Intel P35 that ahs already stood the test of time and has always demonstrated excellent stability during overclocking.
As a result, our testbed was configured as follows:
- CPU: Intel Core 2 Duo E8500 (LGA775, 3.16GHz, 1333MHz FSB, 6MB L2, Wolfdale).
- Mainboard: ASUS P5K3 Deluxe (LGA775, Intel P35, DDR3 SDRAM).
- Graphics card: OCZ GeForce 8800GTX.
- HDD: Western Digital WD1500AHFD.
- PSU: SilverStone SST-ST85ZF (850W).
- OS: Microsoft Windows Vista Ultimate x64.
We overclocked the memory using FSB:Mem divider of 1:2. System stability was tested with Memtest86+ 2.01 and Prime95 25.3.
I would like to point out that since the existing DDr3 memory controllers of Intel P35, Intel X38 and Intel X48 chipsets do not support any FSB:Mem dividers lower than 1:2, you need to overclock the FSB beyond 450MHz in order to clock the memory at 1800MHz. That is why to ensure our overclocker experiments succeed, we reduced the processor clock frequency multiplier from 9.5X to 9x and at the same time increased its Vcore to 1.4V and NB voltage to 1.7V.
The results we obtained during our Corsair Dominator TW3X4G1800C8DF G tests proved up to our expectations. These modules can not only work at 1800MHz, but can also be overclocked to much higher frequencies even without increasing the voltage beyond the nominal 1.8V. By the way, the modules’ reaction to voltage increase beyond the specified 1.8V is slightly different from what we are used to seeing. The thing is that 1GB overclocker memory modules built with Micron chips were pretty sensitive to voltage increase and their overclocking potential went up. Things are different with TW3X4G1800C8DF G: the increase of their voltage past 1.8V hardly affects the result. That is why we first of all tested our memory kit at this particular voltage setting.
Corsair Dominator TW3X4G1800C8DF G overclocked to 1864MHz with default timings of 8-8-8-24 and remained 100% stable.
We obtained this result with Command Rate set at 2T, as stated in the XMP profile. Note that during overclocking to 1864MHz on the memory, when the FSB was set to 466MHz and the CPU frequency was pushed to 4.19GHz, we managed to set the Performance Level parameter to 6. This has definitely affected the performance: the practical read speed made 11GB/s and latency dropped to 47.7ns.