To get the best performance from your rig, its essential to get good parts.
Your CPU, GPU, and RAM all come with default performance levels.
These are generally designed to work in most scenarios, assuming theres enough cooling power to not cause overheating.
Generally, manual overclocking will void the warranty of at least the affected part.
In some cases, overclocking one part can void the warranty on another.
To prevent these sorts of failures, its essential to be careful, especially when increasing voltages.
The performance of your hardware can simply come down to your luck in the silicon lottery.
Generally, manufacturers sort products into different performance bins during testing in a binning process.
With regards to your actual experience overclocking, the key is to try things and then verify stability.
Just being able to boot your box isnt enough.
RAM Overclocking: XMP
CPU is generally the most well-known form of overclocking.
GPU overclocking is a little less common, as GPUs already tend to run near thermal and power limits.
Still, small improvements of around 200MHz can be achieved for minor performance boosts in-game performance.
RAM overclocking is probably the least well-known of the three but might be the most commonly used.
XMP is an excellent option for what is essentially plug-and-play RAM overclocking.
As the XMP profiles are vendor-approved, using them doesnt void your RAMs warranty.
However, as we mentioned above, it can void your CPU warranty.
If you want a simple performance boost with almost no effort, XMP is excellent.
Of course, XMP profiles are often safe choices that the vendor is willing to guarantee.
With some manual experimentation, though, you’ve got the option to usually push them further.
Youll want to run some memory benchmarks and store those values in some format, ideally a spreadsheet.
Aida64s memory tests are a popular tool for benchmarking.
Statistical differences from RAM performance will be much harder to see if youre in a GPU-limited scenario.
While you dont necessarily need to do it every time you change any setting.
Its essential to check that your prefs are stable under long-term load.
In that case, you might generally get away with this at the start.
In that case, you might find this is stable, potentially saving you a fair amount of time.
Only to fall over after 6 hours of stress testing.
As much as stability testing and performance logging may sound and be monotonous and tedious, its necessary.
The time per cycle/cycles per second, and the number of cycles for specific actions.
The number of cycles for these actions is denoted by the memory timings.
This is because it runs at twice the clock speed, allowing for twice as many transfers per second.
The actual memory latency, however, will be the same.
This is because timings are counts in single clock cycles, not absolute values.
Youll need to loosen the timings to further increase your clock speeds.
you might tighten them later but want to do so at the maximum possible clock rate.
This may give you an excellent place to start.
However, you may need to loosen the timings a little further.
Suppose your brand doesnt have a higher-speed variant.
Memory Gear
While technically not overclocking, the memory gear setting can significantly affect your stability.
It can also incentivize you to avoid pushing clocks within a specific range.
By default, memory tends to run at a 1:1 clock speed ratio with the memory controller.
As you push the memory clock speed, the load on the memory controller significantly increases.
This increases heat production and voltage requirements.
High heat and voltage can cause stability issues.
In worst-case scenarios, it can kill your memory controller and thus your CPU.
This is why memory overclocking can potentially void your CPU warranty.
Gear 2 puts the memory controller in a 1:2 ratio with the memory clock.
This significantly reduces the memory controllers load but introduces some extra latency.
Generally, the point at which you should probably enable gear 2 for stability reasons is at 3600MTs.
There you focus on tightening the memory timings further instead.
Note:Gear 4 is technically offered for DDR5.
It sets the ratio to 1:4 for the same reasons with the same drawbacks.
Current DDR5 memory is not fast enough to need to take advantage of Gear 4.
CAS Latency
The standard measure for the RAM latency comes from the CAS latency.
This is often shortened to CL, tCAS, or tCL.
When lowering this value, always keep it even.
Odd numbers tend to be significantly less stable.
Timings are all measures of how many clock cycles it takes to do something.
The absolute time it takes to do something doesnt change as the clock speed increases.
RAM can only open a column in 10 nanoseconds, for example.
Your timings just need to reflect the absolute time in clock cycles.
This may be separated into tRCDWR and tRCDRD, which denote writes and reads, respectively.
The two values should be the same if the values are separated above.
These values dont necessarily need to be even and will generally be slightly higher than tCL.
This has historically been around the value of tRCD + tCL.
You may have success tightening this timer, depending on your platform.
It should be set to at least tRAS + tRP.
Weve not mentioned tRP.
Here as tightening doesnt directly provide much of a performance impact.
It is the minimum number of cycles required to complete a precharge command to close a row.
Only one row can be open per bank.
This helps with pipelining commands.
The minimum value allowed by the memory controller is 4 cycles.
This may be split into two separate timings, tRRD_S and tRRD_L, which respectively mean short and long.
The short value should retain the minimum value of 4 cycles.
The long value is typically twice the short value but may be able to be tightened further.
This is because the power draw of opening a row is significant.
This should be at minimum 4x tRRD_s.
Values lower than this will be ignored.
Time Refresh Command
tRFC is the minimum number of cycles that a refresh command must take.
DRAM, being dynamic, needs to regularly refresh the memory cells lest they lose their charge.
The process of refreshing means that a bank must sit idle for at least the entire duration of tRFC.
Obviously, this can have a performance impact, especially with a small number of banks.
This number is usually relatively conservative and can generally be reduced a bit.
Tightening tRFC too far will lead to widespread memory corruption issues.
Time Refresh Interval
tREFI is unique amongst all the DRAM timings for two reasons.
First, the only timing is an average rather than a minimum or exact value.
Secondly, its the only value that you should probably increase to get increased performance.
tREFI is the average time between refresh cycles, defined in length with tRFC.
This value will be much higher than any other time.
You want it to be as high as possible while remaining stable.
Typical values will be in the ten to thirty thousand cycle range.
However, it can be stable with a maximum value of 65534.
This value must be greater than tRFC.
You should definitely start high and work your way down.
Remember that a number just a little too high may take multiple hours to display stability issues.
This means that if youre going for a high tREFI, you may need to reduce the voltage.
You may also need to ensure your RAM has good airflow.
This can make a previously stable configuration unstable.
Safe voltage
Voltage is always essential for overclocking.
A higher voltage tends to mean a better chance of a stable overclock.
Higher voltage also tends to significantly increase heat production.
It also increases the risk of you killing your hardware, so be careful.
Unfortunately, theres no one safe value.
This is because there are multiple memory IC OEMs whose memory chips perform differently.
Its also partly because numerous voltage controls can helpfully vary in the name.
Typically, you do not want to increase these values by much.
For DDR4, 1.35V should generally be ok for everything.
Some DDR4 DRAM ICs can be perfectly stable even for daily use at 1.5V.
In some cases, a little more can be safe too.
For DDR5, the current-voltage recommendations are the same.
Given the immaturity of the platform, this may change over time.
There are no safeguards or sanity checks here.
Risky Voltage and Undervolting
Suppose you oughta increase your voltage beyond 1.35V to achieve stability.
In that case, its worth researching which die variant from which DRAM IC OEM you have.
Remember, your mileage may vary regarding performance, stability, and critically not killing your hardware.
While you may be able to provide more voltage than is recommended, ideally safely with no issues whatsoever.
Its generally best to undershoot the recommended values a little.
Undervolting is the process of reducing the running voltage.
It typically lets hardware run cooler and safer.
Its more critical for CPU and GPU overclocking.
There the temperature reduction can allow a slight increase in peak clock speeds.
RAM speeds dont adjust with temperature like that, though.
Other Timings
There are plenty of other secondary and tertiary timings that you might fiddle with.
Configuring all of these values to the tightest possible prefs.
You shouldnt take this to mean that the process will be short if you just adjust the recommended configs.
It will be faster, but not short.
Conclusion
There is a broad range of ways to improve the performance of your RAM.
For absolute beginners, XMP is the way to go.
It is excellent as a plug-and-play solution that only needs to be toggled on.
After that, you get pretty in-depth.
The optimization process can take weeks of work to reach the limit of your hardware.
Its also important to be careful.
Overclocking can kill hardware, especially if you increase the voltage by too much.
Which is a win in our book.
