One of the most powerful features available to Ryzen CPUs is Precision Boost Overdrive, or PBO. It's an algorithm built into your Ryzen CPU that dynamically optimizes power and frequency based on some set parameters. You can adjust those parameters, though, and if you have one of the best CPUs in your particular lineup, potentially unlock some performance improvements.

I'll be adjusting PBO settings through the BIOS here because you're given more control (and options) compared to using AMD's Ryzen Master application. PBO inherently makes overclocking simpler, so you don't have a ton of options to begin with. Your BIOS is where you can dig into all the settings PBO has to offer, and you can ensure that your overclock or undervolt sticks around the clock.

6 "Auto" won't do much of anything

Is this thing working?

The moment you stick your head in the BIOS, you'll see that PBO is set to "Auto." I can't say that every motherboard will have PBO set this way, but every board I've encountered is configured like this. That won't do anything for you. This uses AMD's Precision Boost, not Precision Boost Overdrive. Essentially, it allows the CPU to boost areas where it has headroom until it reaches a limit. For example, you can feed more power to the CPU if you're running a bursty workload that's only using a few cores, potentially boosting the single-core clock speed if you have thermal headroom. For the purposes of this guide, you'll want to set PBO to "Advanced" or "Manual."

After you do that, you should see several more settings appear. This is essentially turning PBO on. Most motherboards will come with a setting to enable PBO, but once again, that will dynamically adjust your performance in the background based on the various parameters that PBO tracks. To get the best performance, you'll need to get your hands dirty, and that's exactly what we're doing here.

5 Set your power limits

More power!!!

The first batch of settings you'll see relate to power, and they're the numbers that largely determine what PBO is capable of. Adjusting the power limits won't do anything on its own; you can actually decrease your all-core boost by hitting a thermal wall faster with higher power limits. Adjusting these settings simply gives your processor and motherboard more power headroom to work with when you adjust other settings. There are three power settings you'll see:

• PPT -- Package Power Tracking, which determines how much power in watts the processor can draw from the socket.
• EDC -- Electrical Design Current, which determines the current in amps that the motherboard's VRMs can supply in brief spurts.
• TDC -- Thermal Design Current, which determines the current in amps that the motherboard's VRMs can supply over a sustained period.

Your processor has built-in limits for each of these values, but you can (and should) increase them if you want to get the most performance out of your Ryzen CPU. My motherboard, the Gigabyte B650I Aorus Ultra, actually has a "Motherboard" setting for these values, which caps them off higher than what the PBO defaults to.

As is the case with all the settings here, I can't provide exact numbers. It depends on your CPU, motherboard, case, and cooling solution, and even then, there's variance. Raising the limits here simply allows the processor to draw more power if it needs to. You won't get that extra headroom if a thermal limit kicks in before the power limit does, for example. Many motherboards have a maximum limit for these power levels, which essentially gives the processor as much power as it wants until it hits some other limit, be it thermals, clock speed, or voltage.

In most cases, you'll want to increase the power limits, though you can decrease them as well if you have thermal concerns. For instance, in my small form factor PC, I'm running an undervolt on my Ryzen 7 9800X3D with slightly lower power limits, optimizing the performance for an ideal power budget when playing my (non-CPU-intensive) games.

4 Optimize your Curve

The real power of PBO

The real power of PBO lies in the Curve Optimizer. This is what enables higher performance (and possibly lower temperatures) on a Ryzen CPU. The other settings work to support what you do in Curve Optimizer. Basically, Curve Optimizer is an offset for the voltage/frequency curve of your CPU. By default, your processor has a curve of frequency values and voltage; how much voltage does the processor need to achieve a given frequency? Curve Optimizer allows you to offset this curve, supplying more or less voltage for a given frequency based on a fixed offset.

Curve Optimizer is complex, so let's move in stages. You can adjust the offset on an all-core, per-core, or per-CCD basis, the last of which is only relevant to dual CCD chips like the Ryzen 9 9950X3D. If you're adjusting the offset for all of your cores, you almost always want a negative offset. You're telling the PBO algorithm to use less voltage for any given clock speed. This is undervolting. That term is sometimes used as some sort of antithesis to overclocking, but that's not the case. Undervolting can actually lead to higher clock speeds, as you're able to climb higher before hitting unsafe voltages.

This can represent some decent performance gains depending on your CPU and application. Given the variance in silicon, AMD defines a voltage curve conservatively so that all CPUs that carry the same name can deliver their rated clock speeds. If you have a particularly good CPU, though, there's a good chance you're able to achieve those same clock speeds at a lower voltage. And that, in turn, allows you to push higher clock speeds. I recommend knocking down the all-core offset in increments of 10 to see what your CPU is capable of. Most recent Ryzen chips should be stable with a negative offset of around 20 to 30, but it really depends on your particular CPU.

So, why is there even a positive offset? That's where per-core adjustments come into play. A positive offset won't give you extra performance -- you're using more voltage for a given clock speed -- but it can help with stability. If you're dialing in an offset for each core, you may find that some cores need more voltage than others in order for your PC to remain stable.

Setting up per-core offsets is a very time-consuming process. It will take weeks of trial and error to get the curve dialed in, so you'll need to be patient and willing to constantly jump back into the BIOS to tweak your curve as you go. For most people, you should stick with an all-core offset, at least to start. If you want to go deeper, switch the offset to all-core and make small adjustments, running stress tests with monitoring tools up in between. That way, you'll be able to identify any misbehaving cores and tweak them accordingly.

3 Now shape your curve

A big boost for Zen 5

If you have a Zen 5 CPU, you can use Curve Shaper instead of Curve Optimizer. This is a pretty big addition, and it allows you to easily optimize your voltage/frequency curve across the entire spectrum, rather than optimizing for one area of the curve while leaving another behind. Here's how it works. Curve Shaper separates the frequency into five bands, each of which is further separated into three temperature regions. For each frequency band and temperature region, you can set a positive or negative offset, allowing much more control over the overall shape of your V/F curve.

With Curve Optimizer, you're still using the same V/F curve defined by AMD; you're simply moving it up or down based on your offset. Curve Optimizer gives you far greater control. If you're trying to optimize for maximum boost clock speed, for example, you can define a more conservative offset at lower frequency to maintain stability, while pushing a more aggressive offset as your clock speed climbs. It basically gives you the best of both worlds depending on what your CPU is capable of.

2 Boost clock override

For particularly capable silicon

This is one of the more confusing settings in PBO 2. It sounds like a set frequency boost, but that's not actually how the override works. Instead, the boost clock override simply defines the upper bound of the boost clock speed that PBO is looking at, either positively or negatively. You can set up to a +200MHz override, but that won't boost your clock speed by 200MHz. It'll just allow PBO to achieve clock speeds up to 200MHz higher if you have headroom in thermals and power.

You can set this at +200MHz, and I'd recommend doing so if you're looking for maximum boost clock speeds on one or two cores. Just keep in mind that you aren't actually overclocking the CPU. This is basically a silicon tolerance window, allowing chips with more favorable silicon to boost higher than the rated clock speed.

1 Set your scalar

For the brave (and well-cooled)

This is a bonus setting because, for most people, you shouldn't mess with the scalar in PBO. This increases the Failure In Time, or FIT, value of your processor. In short, it allows you to feed more voltage to the CPU if you're less concerned with longevity, potentially leading to better performance. Every Ryzen CPU comes with voltage ranges that are ideal for the intended lifespan of the chip. The Scalar setting overrides these defaults, allowing you to push higher voltages and thermals for longer periods of time, up to a factor of 10X.

Most people shouldn't increase the default setting of 1X, and that's for two reasons. First, you probably won't see much of a performance benefit. The scalar really only helps out if you need to sustain high frequencies for a long period of time, and you need a cooling solution to support that. That's assuming you can't sustain those frequencies within a normal voltage range, too. On top of that, you are quite literally decreasing the life of your processor. The scalar removes safeguards that are otherwise in place to keep your processor from frying itself up after a year or two.

Still, it's a good setting to be aware of, if nothing else than to avoid it when you're tinkering with PBO settings. There are some CPUs and some cooling solutions where setting a high scalar makes sense, but for everyone else, it's best to leave it as default.

Less is more with PBO

Although there are a ton of options when you dig into the PBO settings in your motherboard, the more moderate adjustments will yield the highest performance gains. A simple all-core offset, slightly higher power limits, and a slightly higher ceiling for boost clock speeds is all you need in most cases. The rest of the options are just about optimizing, rather than directly contributing to big performance wins.

Before you start tweaking, there are a couple of things you should keep in mind. First, you will void your warranty since you're technically running outside of AMD's specifications, but that shouldn't be a big deal as long as you aren't cranking the scalar and hoping for the best. In addition, every CPU and motherboard is different. Some architectures respond better or worse to PBO, and some chips within a generation take particularly well to the feature, such as the Ryzen 7 7800X3D. Like any overclocking endeavor, it's best to start small, validate stability, and gradually increase from there. That's the only way to find out what your specific rig is capable of.