So earlier this week we pointed you to a potential problem with the upcoming Core i7 Nehalem-based processors involving voltages.  Apparently, because the memory controller on the new processor is directly associated with the voltage of the entire processor, DDR3 DIMMs that are reaching over the 2.0v mark could be potentially hazardouse to the CPUs.  This is because the CPU voltage and VDIMM voltages are linked in some fashion.  Anandtech decided to do some investigating to find out what the issue is. 

Our answer at this time is Yes and No. It sounds like we are straddling the fence but in actuality the correct answer depends on the available BIOS options, BIOS settings, memory selection, and final voltage settings. Intel’s stance is clear on this subject, run VDimm higher than their 1.50V~1.65V guidelines and you will affect the life span of the processor.

Exactly what the impact to the processor will be is dependent upon several factors. Put simply, if you go crazy with VDimm, let’s say around 2.0V~2.2V without additional tuning, then expect to greatly reduce the processor lifespan to a few weeks or maybe days. We have already witnessed several CPUs being damaged or destroyed at the motherboard partners with high VDimm settings, especially those that ran at 2.0V or higher with base settings. By base settings, we mean configuring an i7/X58 platform in the same manner a typical user now sets up a Penryn/X48 DDR3 platform. The rules have changed completely for Intel, just we cannot discuss the playbook at this time (hey, it is frustrating for us also).

Likewise, we have seen high VCore/VDimm test beds operate without a problem for benchmarking purposes (yet still fail with long-term bench testing) provided a multitude of BIOS settings for the core, DIMM, IMC, Uncore, and QPI selections were properly set. The base secret (there are more) is maintaining correct amplitude levels, something we will discuss at product launch. For now, high VDimm is not necessarily the true problem here, but it is the quickest way to damage/destroy an i7 if the system is not properly tuned.

However, we highly recommend keeping VDimm at or below Intel’s recommendations along with proper BIOS settings for the long-term health of the i7. Upcoming DDR3 products from the major memory suppliers will all support low voltage DDR3-1066~DDR3-1600 operation with fairly aggressive timings. In addition, the vast majority of JDEC spec DDR3 memory currently on the market will operate fine on the X58, albeit at slightly higher memory timings in some cases.

The extreme performance modules will also operate correctly, as we have found in testing to date, just at higher timings in order to meet the voltage guideline requirements. Certain performance modules that require 1.8V or higher upon POST will probably not work correctly (POST) unless the board manufacturer steps outside of Intel’s guidelines. In that case, you can replace the memory, reflash the SPD if the supplier allows, or toss in a pair of JDEC spec modules (current 1066 is fine), correctly set the voltages and timings that you require in the BIOS, shutdown, and reboot with the performance modules. Realize, this does place you outside of the guidelines but most users that fall in this category are already outside the lines anyway.