OCZ ReaperX HPC PC2-6400 Memory 4 Gig Kit
Author: Frank Stroupe
Editor: Shawn Knight
Date: 01-17-2008
Provided by: OCZ Technology

Test Rig:

Intel Q6600 Core 2 Quad G0 stepping
Asus P5K Deluxe Wifi-AP Intel P35 motherboard
Zotac 8600GTS Video Card
Rosewill Xtreme 850 watt PSU
OCZ Vendetta CPU Cooler
Zalman VF-1000 GPU Cooler
Vista Home Premium 64-bit

Both the Q6600 and the P5K have proved to be excellent overclockers, when coupled with the right memory. I've been running the processor at over 3 gigs for a while with some PC2-10000 memory. At one point, I had a 2 gig kit of OCZ Reaper PC2-6400 in this rig, and I really didn't have very much luck with overclocking; I never got it over about DDR2-950.

Keep in mind that to utilize 4 full gigs, you must use a 64-bit operating system. I will be using Vista Home Premium 64-bit.

I started by installing one stick at a time and running Memtest86 overnight. Memtest found no errors on either module.

Before doing any real testing, I just checked things out, how my system performed with 4 gigs of memory. The improvements were easily noticed; Vista loaded faster and performed better. I had bought Crysis a few days before, and had played it probably 8 hours or so. My rig performed well with Crysis, even with 2 gigs of memory. After installing the ReaperX, it felt like my rig really opened up and started to breathe. The game loaded in half the time and individual levels loaded nearly instantly. By this time I could really see that I was going to like running 4 gigs of memory.

Though overclocking memory is important to most enthusiasts, I feel that finding a memory's flexibility is just as important. Not all rigs overclock well, but performance gains can be had by tightening timings at stock operating frequency. Also, I wanted to see how the memory will perform at lower voltages, to see if it is flexible enough to be used in motherboards that do not have a memory voltage option of 2.1v or better.

A quick look at CPUZ showed that the default timings for the P35 chipset are quite loose, 6-6-6-18, so my first testing will be with timings. I'll try to tighten them up some at the 2.1v stock voltage.

The only change that I will make besides setting the main timings is one of the recommended tweaks from the P35 tuning guide that OCZ's site linked to. The tester recommended that the Write to Read Delay, also known as tWTR, be set to 11. I'm going for it all the first try, to 4-4-4-15.

Man… what a difference tightening the timings made. Vista loaded the fastest that it has since I installed it. The ReaperX had no problems running at those timings. I played around with some ~1 gig files in PhotoShop, played some Crysis, ran some memory benchmarks... everything ran fine.

Next, I lowered the memory voltage to see if we can maintain those timings at lower voltages. My rig wouldn't boot at 1.8v. It did boot up and run at 1.85v, and ran the benchmarks ok, but crashed during Crysis. At 1.9v, everything ran fine.

I also check to see if I could boot up at all at 1.8v. It booted fine with 5-5-5-15 timings.

The last timing test I ran was trying to see just how low of timings I can get at stock frequency. I upped the voltage back to 2.1, and tried to get CAS 3. I couldn't get the rig to boot at CAS 3, even with upping the voltage to 2.2v, but I did get the advertised 4-4-3-15 at stock voltage.

I'm pretty satisfied with the ReaperX's flexibility, so let's do some overclocking.

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