Memory (RAM) Overclocking Guide - DDR3

Usually, when overclocking is brought up, the CPU gets most of the attention. But if you're overclocking, why should you stop there. You can also overclock the memory (RAM) and video card to achieve even better performance, so today, we're going to focus on overclocking the memory.

RAM can be overclocked in two ways: increasing the speed it's running at or lowering (tightening) its timings. We'll cover both methods in this guide, since you'll usually use a combination of them both to reach your maximum overclock.

We're also going to touch on some the best ways to optimize your overclocked system (once you know your maximum BCLK, processor, and memory speed), so you'll be able to realize the highest levels of performance.

Understanding the Basics

This guide picks up where we left off in our last one ( How to Overclock - Intel Core i7, i5, i3 CPU Overclocking Guide) and assumes that you've already successfully overclocked your CPU.

If you haven't overclocked your processor yet, we'd recommend that you do that first, and the guide we just mentioned will teach you everything you'll need to know to be able to do that.

Before you get started, it's good to fully understand the basics of how everything works, so you'll know what you're doing. In this section, we'll go over what determines the RAM speed and how the memory timings work.

What Determines the RAM Speed?

RAM Speed = Base Clock Rate * Memory Multiplier

If you remember from the last guide, the base clock rate (BCLK) is used to determine the speed of many other components in the system, including the memory and CPU. So, to overclock your ram, we'll just need to increase BCLK or the memory multiplier.

Understanding Memory Timings

Your ram also uses a variety of timings to control how fast it operates, and it's important to understand these timings before overclocking your memory.

You can read more about them in the following short guide: Memory (RAM) Timings & Latency: CAS, RAS, tCL, tRCD, tRP, tRAS.

Hardware We're Using for this Guide

For this guide we're using the following ram:
G.SKILL ECO Series F3-12800CL7D-4GBECO 4GB (2 x 2GB) DDR3-1600 7-8-7-24 1.35v

It's rated to run at 1600 MHz with timings of 7-8-7-24 at only 1.35 V. This memory is excellent for overclocking because it only needs 1.35 V (standard RAM runs between 1.5 - 1.65 V), so we'll have a lot of room to overclock this. It's also running at pretty tight timings, so that should also allow us to be able to overclock with lower latencies.

And if you're interested, here's the rest of the hardware we're using to overclock our system:

CPU Intel Core i5-760 2.8GHz LGA 1156 95W Quad-Core Processor
Cooler CORSAIR CWCH50-1 120mm High Performance CPU Cooler
Motherboard ASUS P7P55D-E Pro LGA 1156 Intel P55 SATA 6Gb/s USB 3.0
RAM G.SKILL ECO Series 4GB (2 x 2GB) DDR3-1600 7-8-7-24 1.35v
Video Card GIGABYTE GeForce GTX 460 (Fermi) 1GB GDDR5 GV-N460OC-1GI
Storage Crucial RealSSD C300 CTFDDAC128MAG-1G1 2.5" 128GB SATA III MLC SSD
Power Supply CORSAIR CMPSU-750TX 750W
Case Antec Nine Hundred Two
Monitor ASUS VH242H Black 23.6" 5ms HDMI Full 1080P Widescreen LCD w/Speakers
OS Microsoft Windows 7 Home Premium x64

Getting Ready to Overclock the RAM

Make Sure Your Memory is Stable

Before we get started, it's probably a good idea to test the stability of the memory, so you'll know you aren't trying to overclock something that's already unstable.

Memtest86+is a good program for testing your ram. Make sure you're able to complete at least one full pass without any errors.

If you're getting errors at this point, make sure your memory is running at its correct timings and voltage (as specified by your RAM manufacturer).

Set Your RAM to its Maximum Multiplier

This can be accomplished by either directly increasing the RAM speed to the maximum the BIOS will allow (at its current BCLK), by increasing the memory multiplier, or by lowering the RAM ratio. The method you'll need to use depends on your particular BIOS.

Decide How High You Want to Push BCLK

We now have two options for overclocking the ram:

  1. Overclocking up to your current BCLK (the one you're currently using to overclock your CPU).
  2. Overclocking up to your maximum BCLK (the one you determined when you were determining your system's theoretical maximum BCLK).

If you overclocked your processor using a fixed multiplier, you could possibly lower your CPU multiplier and up your BCLK to achieve the same processor speed. This may also let you run your memory at a higher speed than you'd be able to otherwise.

If you didn't figure out your maximum BCLK when you overclocked your CPU and want to learn what it is, then read Determining Your Maximum BCLK (Base Clock) Frequency - i7, i5, i3.

If you're:

  1. Running at lower than your maximum BCLK.
  2. Using a fixed processor multiplier (i.e. turbo boost is disabled).
  3. And haven't tried lowering your CPU multiplier to achieve your overclock at the highest possible BCLK.

You should probably try to overclock your RAM up to your maximum BCLK. In this case, set your VTT voltage to the amount that's necessary for your maximum BCLK.

However, if you're not in the situation mentioned above, you should probably save yourself the hassle and just overclock your memory up to your current BCLK. In this case, just leave your VTT voltage at whatever it was before you tried to overclock your RAM.

Lower BCLK Until Your Memory Speed is at its Default

If you're running RAM that's rated at 1600 MHz, you'd want to set BCLK to 1600 / 10 = 160, where 10 is your maximum memory multiplier. For 1333 MHz RAM, set BCLK to 1333 / 10 = 133.

Lower Your CPU Multiplier

If you're just overclocking your RAM up to your current BCLK (as determined above), you can skip this step and move on to the next section Determining Our Maximum RAM Speed, since your processor shouldn't cause any problems.

However, if you're overclocking to your maximum BCLK, you'll need to lower your CPU multiplier, so it won't get overclocked any higher as we overclock the memory.

The multiplier you should use is pretty easy to calculate, as shown below:

CPU Multiplier = Maximum Overclocked Processor Speed / Maximum BCLK.

So if your maximum overclocked CPU speed was 4.0 GHz and your maximum BCLK was 210, you'd want to set your processor multiplier to 4000 / 210 = 19.05. Round this down to the nearest whole number, which (in this case) is 19.

Make sure that you leave your current cpu voltage ( vcore) at what it was before you started overclocking your memory, since we don't want to have to worry about the CPU affecting our RAM overclock.

Determining Our Maximum RAM Speed

Now that all of the preparation is out of the way, we can move on to actually overclocking the memory.

Although we haven't overclocked the RAM yet, it's still a good idea to run about 5 minutes worth of Memtest86+ (just to make sure we're still stable).

Now, increase BCLK by 10 and run another 5 minutes worth of Memtest86+. If it fails, go back to the BIOS and increase your ram voltage (usually called DRAMor VDIMM) by 0.025 V and run the test again. If it passes, increase BCLK by another 10.

Important: Make sure your DRAM voltage never goes more than 0.5 V over your VTT voltage. If you need to increase VTT to enforce this rule, then go ahead and do it as long as you haven't reached your maximum safe VTT. Intel's absolute maximum for VTT is 1.4 V.

Keep doing this until you hit one of the following road blocks:

  1. You hit your maximum DRAM voltage. Intel's absolute maximum for the memory voltage is 1.8 V, but they recommend that you don't go over 1.65 V.
  2. You reach your maximum BCLK.
  3. Increasing the RAM voltage doesn't increase your stability.

If you haven't hit the maximum you're willing to push the memory voltage and increasing it doesn't seem to help anymore, you can try increasing the VTT voltage to see if this helps. If it does, keep going with the previous process until you hit one of the limits.

However, if you reach your maximum DRAM voltage and you still aren't at the RAM frequency you'd like, you have another option: increasing (loosening) the memory timings. This will usually allow you to increase the RAM speed even higher.

Loosening the RAM Timings to Achieve a Higher Memory Frequency

Now that you've learned everything you need to know about what all of the timings mean, you'll be able to change them to yield a higher overclock (if you haven't reached your BCLK limit yet).

For now, increase the first three timings (tCL, tRCD, tRP) by 1 and the last timing (tRAS) by 3, so if your original timings were 7-8-7-24, they should now be 8-9-8-27. This should give you a little extra room to overclock the memory at its current voltage.

Once you've increased these timings, continue with the previous overclocking procedure, and if you hit another road block, you can keep increasing these timings in this way until you achieve your maximum RAM frequency or hit your maximum BCLK.

Determining Our Maximum RAM Speed (continued)

After you've hit your limit by increasing BCLK by 10 at a time, go back to your last stable BCLK, and increase it by 5 this time. If this passes, go up by 2. If it doesn't, go down by 2. After a few tries, you should be near your maximum memory frequency.

Once you think you've found your maximum frequency, you'll want to start running a stress test that's longer than 5 minutes, such as at least 1 full pass with Memtest86+.

We're not done with the stress testing at this point, but before we continue, let's go over some strategies for getting the most out of your overclocked system (as a whole).

Optimizing Your System for the Highest Performance

You've now found your maximum memory speed, but what if it requires a BCLK that's too high for your current cpu multiplier? What's the best way to simultaneously optimize the cpu, memory, and system as a whole?

Well, we have another short guide on this subject: Optimizing Your Overclocked System for the Highest Performance, so if you're interested, take a look at it before moving on.

Tightening Your Memory Timings

Well, we're almost done. There's just one last thing to do: tighten the memory timings, which will allow your ram to run at its best (given its current frequency).

You can find out how to do that in the following short guide: Tightening Your Memory (RAM) Timings.

Final Thoughts

You now know pretty much everything there is to know about overclocking your memory (and your system as a whole if you read How to Overclock - Intel Core i7, i5, i3 CPU Overclocking Guide).

We covered both of the main methods for overclocking your RAM: maximizing its frequency and tightening its timings. And we also talked about optimizing your system as whole, so you should be covered on all of the bases.

If you have any questions or comments on the article, feel free to leave a comment below.