• Beau Steward

Intel's Superiority Is Built On Lies

Let me get this first thing straight: Intel hasn't really done anything...wrong. I'm not accusing them of any wrongdoing. I'm attacking a specific feature of their CPUs which causes a great deal of confusion and frustration. Yeah, that means this is a little clickbaity.

I'm attacking Turbo Boost and how it relates to their TDP ratings.

First, what is TDP? It stands for Thermal Design Power. This is the amount of thermal waste expected from the CPU package and informs the amount of cooling required for the CPU to operate within its parameters. It also gives an idea of its power requirements. A CPU's thermal output can vary based on load, and certain features can cause it to exceed the TDP. One such feature from Intel is Turbo Boost.

Turbo Boost sounds great on paper: The CPU has a base clock at which it's known to run most efficient, and it can boost to higher clocks for short periods of time for better performance at the cost of higher thermal output. It's intended to be for temporary demands on power.

Intel's TDP ratings, which they advertise for their CPUs, is based on the base clock. Laptop CPUs tend to have a lower base clock than desktop CPUs. It's pretty common to see a laptop CPU with a base clock of 1.6 GHz, while the desktop equivalent has a base clock of, say, 3.4 GHz. But both can have a Turbo Boost capacity up to 4.2 GHz. To achieve that boost, though, requires increasing power to the CPU. This is important to note because that laptop CPU may have a 15W TDP rating while that desktop part has a 65W TDP rating, but Turbo Boost may push it beyond 100W.

Note: I don't have real world numbers. There are plenty of tech bloggers and Youtubers that do. These are just examples.

So how does this give Intel superiority? It means these CPUs have really good performance overall. But why call it a lie? Because the performance isn't always available and some tricks were implemented to improve thermals and the ability to cool them. With variable clock rates, this shouldn't be a problem. Shouldn't be.

Let's go back to that 15W laptop part with a base clock of 1.6 GHz and a Turbo Boost of 4.1 GHz (Intel Core i5 8365U). The 15W TDP is based on a full load at 1.6 GHz. The desktop equivalent is 65W with a base clock of 3 GHz and also Turbo Boosts to 4.1 GHz (Intel Core i5 8500). It's fairly safe to assume that if the laptop part runs at 3 GHz, it will also put of 65W of heat, over 4 times the amount of its rating. But it can go all the way to 4.1 GHz. If doubling the clock quadruples the heat output, it's probably safe to assume that a full Turbo Boost puts it past 100W.

Why is this a problem? As I mentioned, the TDP informs of cooling requirements. In a desktop, it's easy to go way overkill on cooling because there's plenty of room for ventilation and heat dissipation (heat sink, water cooling, etc). Laptops are much more constrained.

And the really tough part of this whole problem is Turbo Boost is, typically, enabled by default, and requires technical know-how to turn it off.

Let's go ahead and call out a company who built a laptop to the technical specs: Dell, with the Latitude 7400. There're many complaints that the fun always runs loudly. I'm among those with this complaint. I decided to try cleaning out the fan to see if that would help (the laptop isn't really all that old) and discovered something shocking: the cooling hardware is grossly inadequate for a 4.1 GHz processor, but may be fine for a 1.6 GHz part. I disabled Turbo Boost, which means my laptop now only runs at 1.6 GHz at peak (lower overall performance), but it's finally quiet.

One could easily blame Dell for this. In fact, I do blame Dell because they know better. But at the same time, the cooling solution is fine for the documented specifications of the CPU. And the CPU is running at the default settings as supplied by Intel. Intel told Dell that this CPU has a specific TDP and that informed Dell of the cooling solution for that TDP.

But at the end of the day, Intel supplied a part with a much higher thermal output than the specified TDP and Dell built a computer with a cooling solution that can't handle it.

As I mentioned, this is something that's turned on by default. Intel voids warranty if you overclock, but Turbo Boost isn't considered overclocking. A big part of voiding the warranty is you are causing the CPU to exceed its thermal design, and you may not have adequate cooling to prevent damage. But Turbo Boost already does this.

In my case, it seems the cooling solution from Dell and the thermal throttling protection in the CPU kept the temperature below damaging levels. But it also means the clock was all over the place, and a fan is running at levels that is annoying and disruptive at best, and may cause hearing damage at worst due to the fact it almost never throttles the fan back down once it gets going. This being a business laptop, there's much more going on than "running a web browser and checking email" so I can't expect it to ever be idle while I work. Yet, it was even the loudest system in my home outside working hours.

So I spent a lot of time attacking Intel, but what about AMD? Well, they don't fully escape from this, either. However, AMD does provide a parameter that helps better inform cooling needs called PPT (Package Power Tracking). AMD's TDP numbers are much closer to reality, and can inform of an adequate cooling solution for most workloads. AMD is just getting back into the laptop arena, so we'll see how they fare there. I'm just really frustrated that it took so much effort to get my laptop usable and not causing me headaches.

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