Our stability testing methods for memory have been discussed at length in the past, so we are going to simply rely on the explanation from previous reviews. Here is a run-down of what we consider to be proper stability testing.

Memory stability, what constitutes stable? What is not considered stable? These questions get hotly debated in enthusiast forums all over the internet like little brush fires on the fringe of an inferno that play havoc with forest fire crews. Everyone has their own opinion about stability, especially when it comes to memory stability. For some, stable means they can do whatever it is on their computer without it crashing, blue-screening, or restarting; whether that means gaming or just surfing the internet. To this user, stable means simply using the computer as they normally would.

Of course, that is not what we would call stable and we do a lot more thorough testing before labeling a memory frequency/timing stable. One of the toughest types of programs on a system has been found to be distributed computing projects such as Rosetta@Home, Folding@Home, World Community Grid, and more. Running 24/7 crunching for one of these great causes is a sure way to find holes in a system if there is truly some instability, unfortunately it takes a considerable amount of time to use them for stability testing so we use the list of programs below to all but guarantee the system to be 24/7 distributed computing stable:

• Multiple loops of 3DMark 01 / 06 (30 minutes of looping the full tests each)
• Dual 32M runs of SuperPi Mod 1.5 (ran at the same time)
• 2 hours of dual Prime95 using Prime95 v25.5 Stress Testing Blend
• 2 hours of dual HCI MemTest Pro in Windows using 850MB/instance

For those use to seeing reviews with a CPU-Z screenshot and a comment that the system was "solid as a rock", you will be quite surprised to see the above testing in the screenshots below. Every overclock of our memory sample listed in this section has gone through this testing. Naturally just because our sample has clocked this well, doesn't mean that every sample will. On the flip side, many samples of this memory will overclock much higher than ours did so it goes both ways.


Specification Stability Testing:

This section was implemented a few reviews back based on the fact that some of the recent memory offerings from manufacturers was having trouble hitting the rated frequencies on the motherboards they outlined it could run on. It seemed that not only did we need to stability test our overclocks but also to thoroughly test the specified ratings at the actual specified voltage. With this Patriot Viper Extreme kit being the absolutely highest rated frequency DDR3 memory we have yet to see here at Hardware Canucks, this section is an absolute must.

It was mentioned previously that we were surprised to see this memory rated for 933MHz operating frequency on P35 motherboards because it has been noted in a number of enthusiast forums that DDR3-1900 is tough to get stable on a number of P35 based motherboards. This doesn't give the folks at Patriot a whole lot of breathing room with this memory. Our particular Asus P5K3-Dlx sample has no problem running memory stable up to 950MHz so it is up to the task, let's see how the Patriot Viper Extreme did at rated frequency/timings/voltage against our stability testing.

If you noticed in the screenshot, we actually forgot about this kit a couple of times during stability testing. Once when 3DMark 06 was looping as it ran for an extra half hour over normal testing and then again during the last program ran, HCI Memtest. HCI Memtest has proven to usually be the measuring stick for total stability and as seen, this kit has no problem running it for hours on end at the rated frequencies and timings. The other thing we wanted to talk about was the voltages used.

In this and all screenshots we have posted today, Asus AI Suite shows the voltage that is set in the BIOS. For the above testing it was obviously set to 1.85v. This, however, equates to 1.91v actually being supplied to the memory which is what the Viper Extreme are rated for. This is what we mean by actual voltage, designated by (A) in the overclocking section. So again, we don't list the voltage by what is set in the BIOS, but the actual voltage which is measured by a calibrated UEI DM393 digital multi-meter and taken directly from the DIMM slots. All motherboards are different and some may over-volt, some may under-volt what is set in the BIOS, this is why we use a digital multi-meter for measuring as it is the only actual way to tell.

Keeping in mind the fact that all voltages listed are marked with an (A) for actual, let's have a look at the overclocking results.:

Right off the top we have to talk about the 8-8-8 results. It is pretty obvious that the motherboard is limiting the overclocking here. There is barely any improvement going from 1.91v(A) to 2.06v(A) and that is a sure sign of the motherboard running out of gas. Previous samples of memory had no problem pushing this P5K3-Dlx to 960MHz stable so it appears it plays favorites with certain memory or is slowing degrading. Either way, this kit potentially has a lot more in it than the P5K3-Dlx is able to provide. We will note that tightening timings up to 8-7-6 or even 8-7-7 didn't have favorable results. Our sample seemed to only like 8-8-8 timings at this high frequency.

As for the 7-7-6 and 6-6-5 overclocking, they are certainly not being limited by the motherboard and this kit of ours really shines, especially at 6-6-5 reaching the magical 800MHz or DDR3-1600 mark. To compare this kind of overclock to DDR2 you would say it is like reaching DDR2-800 at 3-3-3 timings with reasonable voltage. It comes as a bit of a surprise that there haven't been many PC3-12800 6-6-6 kits offered by manufacturers but with modules like these Viper Extreme performing like this at 2.06v, it won't be long until we see more. Reaching DDR3-1844 at 7-7-6 with only 2.06v puts these modules right up there with the big boys from Corsair and Super Talent that are rated for DDR3-1800 at 7-7-7 with 2.0v.