4GB (2x2GB) DDR3 memory at SPD settings and 1,333MHz
Intel Core i7-870
Asus Maximus III Extreme (P55, 0309 BIOS)
650W Seasonic X-Series PSU
1TB Seagate Barracuda 7200.12 HDD
ATI Radeon HD 5770 1GB
ATI Catalyst 10.1 WHQL
Windows 7 Home Premium x64
Memory - Voltage (Intel)
Desktop (idle), Prime95 blend torture test (load)
Samsung 1.85V 1,333MHz
OCZ 1.65V 1,333MHz
OCZ 1.5V 1,333MHz
Kingston LoVo 1.35V 1,866MHz XMP
OCZ 1.35V 1,333MHz
Kingston LoVo 1.35V 1,333MHz
Kingston LoVo 1.25V 1,333MHz
Kingston LoVo 1.20V 1,333MHz
Watts (lower is better)
As you can see, the benefits continue as we increasing drop the voltage from 1.35V to 1.25V to 1.2V - the minimum the Asus board would offer. At the standard SPD of 1,333MHz there was a repeated saving of 5W, or 3 per cent, with every notch of voltage dropped.
When we set the XMP profile, the Kingston LoVo was still impressively power-frugal at 1.35V under load. However, invoking the XMP profile did overclock the Base Clock to 156MHz and automatically increased a few other CPU-related voltages - this offset the idle power saving, increasing it by nearly 30 per cent. That's always the price of overclocking, and we continue to recommend basic 1,600MHz CL9 kits since our Lynnfield memory performance investigation.The 3W difference between the Kingston and OCZ memory at 1.35V is probably due to the DRAM IC used, as the Kingston kit is hot off the SMD line versus OCZ's kits which we've had since last October.
To put the power savings above into perspective, we saw only a 17W difference between a pimped out ATX motherboard and a basic micro-ATX when checking the power efficiency of motherboards. We saw a drop of 24W from the OCZ kit set to 1.5V at 1,333MHz (the default voltage and frequency of DDR3 memory for an LGA1156 Core i7 CPU) to the Kingston LoVo kit at 1.2V and 1,333MHz. That's a comparatively massive saving in power consumption.
In addition to the 1,866MHz kit we have here, Kingston will also release lower priced 1,333MHz and 1,600MHz options that will be worth keeping an eye out for. Check here to see where if you are interested. Kingston says that the LoVo kits will hit the shelves soon, but we still don't have a confirmed date or price for any of the kits.
While the LGA1156 Intel CPUs all support this low voltage memory, BIOS support is imperative as otherwise you might not be able to set such low memory voltages - you need to check before you buy. Motherboard memory vendors should regularly update their QVL (Qualified Vendor List) lists for memory on their website, and Kingston told us it's currently working with motherboard vendors to enable compatibility. We would suggest checking the Kingston website, but it's still about as useful as a chocolate teapot in a desert when it comes to clearly stating which motherboards do and do not support its memory.
Many companies are now pushing out 1.35V kits into the market, but this is often done with less fanfare than their latest high frequency offerings. In addition, some companies - such as OCZ above - haven't branded their 1.35V kits that clearly: OCZ adds its Low Voltage branding to any kit rated at 1.65V or below on its DDR3 products, for example.
This is further backed up by the fact that we found all memory company websites are designed to list modules by performance and not by voltage. Evidently this is something that needs to change, as performance differences between frequencies and latencies have become largely negligible in the real world, while lower voltage memory does have tangible benefits. Not only will your PC draw less power (and save you money) but as the memory controller of the CPU can run with less voltage, your CPU won't run as hot and your CPU cooler will be quieter.