3 ms·

I'm not so sure I agree. My old laptop (still in use) is a Dell Precision m4800. It has a quad-core i7, and is so thick and heavy the word "laptop" is kind of a

I'm not so sure I agree. My old laptop (still in use) is a Dell Precision m4800. It has a quad-core i7, and is so thick and heavy the word "laptop" is kind of a joke. It has massive heatsinks and fairly loud fans. Still it will throttle back after ~90 seconds of "make -j 4" or other heavily parallel jobs. If you have a laptop that will run at 100% load indefinitely, it's only because the manufacturer has chosen a low power CPU.

gambiting 7y ago
Well, then you need to look a little bit longer around the market. At work we use Eurocom laptops with desktop-grade i7 and i9s rated at 90W of power - and we use them for conferences and trade shows to run our demonstrations, they do absolutely fine under full load. Sure they weigh about 5KG, but that's absolutely fine for the target use. I hope that answers the question of "why would you possibly want to do that". I have a Razer Blade Stealth, 13" laptop where the manufacturer has actually gone against the advice from Intel, and gave the CPU a budget of 25W instead of the advised 15W - and the cooling to work with that. Both the CPU and GPU can be at full load indefinitely and will not throttle. It's just a well designed dual-fan cooling solution. My wife has a Lenovo Y540 - with an i5-9300H, 45W CPU - again, the cooling on it is super beefy and it will run indefinitely at full load. And that's a completely normal 15.6" laptop. But you know what throttles? Laptops like the MacBook Air, where Apple used a Y-series CPU and gave it zero cooling - that will throttle hard after a while. And that's a 5W chip. It's almost an achievement that they managed to mess this up. But maybe they shouldn't feel too bad - a lot of other companies do mess it up too. Dell XPS. HP Envy. Those are top lines for these brands and they are famous for aggressive throttling under load. My point is - of course there are laptops on the market that are designed for sustained full load and are completely absolutely fine with it. I'm just baffled by 1) how can this not be obvious 2) how can it be hard to think of one usecase where that's useful?
- semi-extrinsic 7y ago
  Those Eurocom laptops look neat, thanks for the tip. I'm just a bit surprised if they manage to squeeze out significantly better thermal performance than Dell does out of a similarly bulky laptop. Have you actually verified the core frequencies over time with a tool like CPU-z when running a workload that pegs all cores at 100%? The Precision model I have doesn't stutter or feel any slower under load. I've never managed to make it feel slow, even when running heavy physics simulation codes on all cores in the background. But when you actually monitor frequencies, you see it clocks down by around 20%.
  - gambiting 7y ago
    Right, let's clarify what I mean by "throttling". All intel CPUs have base and turbo speeds, and the turbo speeds usually only apply to a single core or to multiple while there is thermal headroom. By "throttling" I do mean the CPU falling below its base frequency to protect itself, I don't mean the turbo frequency falling down under load, that's normal and happens even on desktop CPUs with ample cooling. As an example - the CPU in the Razer Blade is an i7-8565U, with base speed 1.8GHz, turbo speed 4.6GHz. Under maximum load I'll see it jump to 4.6GHz briefly, and then settle at 3.2GHz where it will remain indefinitely. Sure, the CPU has "throttled" down from its maximum turbo speed, but it's stable at 3.2GHz on default cooling. In comparison, I used to own an MSI GT63R with a quad core i7(2630QM if I remember correctly) and that CPU would "throttle" by regularly falling down to 400-600MHz(!!!) as a result of stretched thermals. It was not "stable" at neither its base nor turbo speeds. That behaviour still happens(in the mentioned Air, or an XPS 15 for instance) but there are definitely laptops which don't do that at all.
    - semi-extrinsic 7y ago
      Ah, okay, then I'm using a different definition of throttling. Intel will publish as you say a base speed of 1.8 GHz, then a single core Turbo speed of 4.6 GHz and also an all-core Turbo speed of 4.2 GHz (numbers made up, but something like this). If sufficient cooling is available, the CPU should be able to sustain the all-core Turbo number indefinitely. If it can't, I call that throttling. It can be mild (if you go from 4.2 to 3.2) or severe (if you go from 4.2 to 1.8). A colleague has the XPS 15 (well, the Precision equivalent) and he's never seen it drop below base clock, the problem with it is that base is something ridiculously low like 1.2 GHz. If a machine drops below base freq. due to thermal issues, it has been designed ver wrongly. Our workstations with water cooling run at maximum all-core Turbo freq. for days on end. Those CPUs do exceed the specified TDP when doing so, which is fine as long as the cooler can easily dissipate that heat. And you can get water coolers that support 500W TDP, so no worries. The only guarantee Intel makes is that the processor will stay within TDP when running at the base clock. What's happening when your laptop goes briefly to 4.2 GHz is that it exceeds both the Intel-stated TDP and the cooling system TDP. Then it throttles back to 3.2 GHz, which is a little below the cooling system TDP but above the processor TDP. In a laptop like the XPS 15, the cooling system TDP is only a little higher than Intel-stated TDP. The momentary thermal headroom between what the CPU puts out at max Turbo and the cooling system TDP is provided by the heat capacity of the metal in the heatsink/heatpipe.
karolist 7y ago
My Lenovo W530 still has a socketed CPU which I've replaced from 2 core/4 thread i5-3210M to 4 core/8 thread i7-3610QM and it will happily chug along without down throttling in parallel compilation, benchmarks or games using eGPU. It's a 45W TDP CPU and there are stronger ones doing fine still. And before you say "that's outdated" - well not really https://browser.geekbench.com/processors/753 https://browser.geekbench.com/processors/753, it's about as fast per core as 2013 retina MBP and has 4 real cores. I guess my point is "you can make it work". Now, my work's 2018 15" MBP is suffering massive overheating problems and throttling down just on some light work + YouTube.

gambiting 7y ago

Well, then you need to look a little bit longer around the market. At work we use Eurocom laptops with desktop-grade i7 and i9s rated at 90W of power - and we use them for conferences and trade shows to run our demonstrations, they do absolutely fine under full load. Sure they weigh about 5KG, but that's absolutely fine for the target use. I hope that answers the question of "why would you possibly want to do that". I have a Razer Blade Stealth, 13" laptop where the manufacturer has actually gone against the advice from Intel, and gave the CPU a budget of 25W instead of the advised 15W - and the cooling to work with that. Both the CPU and GPU can be at full load indefinitely and will not throttle. It's just a well designed dual-fan cooling solution. My wife has a Lenovo Y540 - with an i5-9300H, 45W CPU - again, the cooling on it is super beefy and it will run indefinitely at full load. And that's a completely normal 15.6" laptop. But you know what throttles? Laptops like the MacBook Air, where Apple used a Y-series CPU and gave it zero cooling - that will throttle hard after a while. And that's a 5W chip. It's almost an achievement that they managed to mess this up. But maybe they shouldn't feel too bad - a lot of other companies do mess it up too. Dell XPS. HP Envy. Those are top lines for these brands and they are famous for aggressive throttling under load. My point is - of course there are laptops on the market that are designed for sustained full load and are completely absolutely fine with it. I'm just baffled by 1) how can this not be obvious 2) how can it be hard to think of one usecase where that's useful?

semi-extrinsic 7y ago
Those Eurocom laptops look neat, thanks for the tip. I'm just a bit surprised if they manage to squeeze out significantly better thermal performance than Dell does out of a similarly bulky laptop. Have you actually verified the core frequencies over time with a tool like CPU-z when running a workload that pegs all cores at 100%? The Precision model I have doesn't stutter or feel any slower under load. I've never managed to make it feel slow, even when running heavy physics simulation codes on all cores in the background. But when you actually monitor frequencies, you see it clocks down by around 20%.
- gambiting 7y ago
  Right, let's clarify what I mean by "throttling". All intel CPUs have base and turbo speeds, and the turbo speeds usually only apply to a single core or to multiple while there is thermal headroom. By "throttling" I do mean the CPU falling below its base frequency to protect itself, I don't mean the turbo frequency falling down under load, that's normal and happens even on desktop CPUs with ample cooling. As an example - the CPU in the Razer Blade is an i7-8565U, with base speed 1.8GHz, turbo speed 4.6GHz. Under maximum load I'll see it jump to 4.6GHz briefly, and then settle at 3.2GHz where it will remain indefinitely. Sure, the CPU has "throttled" down from its maximum turbo speed, but it's stable at 3.2GHz on default cooling. In comparison, I used to own an MSI GT63R with a quad core i7(2630QM if I remember correctly) and that CPU would "throttle" by regularly falling down to 400-600MHz(!!!) as a result of stretched thermals. It was not "stable" at neither its base nor turbo speeds. That behaviour still happens(in the mentioned Air, or an XPS 15 for instance) but there are definitely laptops which don't do that at all.
  - semi-extrinsic 7y ago
    Ah, okay, then I'm using a different definition of throttling. Intel will publish as you say a base speed of 1.8 GHz, then a single core Turbo speed of 4.6 GHz and also an all-core Turbo speed of 4.2 GHz (numbers made up, but something like this). If sufficient cooling is available, the CPU should be able to sustain the all-core Turbo number indefinitely. If it can't, I call that throttling. It can be mild (if you go from 4.2 to 3.2) or severe (if you go from 4.2 to 1.8). A colleague has the XPS 15 (well, the Precision equivalent) and he's never seen it drop below base clock, the problem with it is that base is something ridiculously low like 1.2 GHz. If a machine drops below base freq. due to thermal issues, it has been designed ver wrongly. Our workstations with water cooling run at maximum all-core Turbo freq. for days on end. Those CPUs do exceed the specified TDP when doing so, which is fine as long as the cooler can easily dissipate that heat. And you can get water coolers that support 500W TDP, so no worries. The only guarantee Intel makes is that the processor will stay within TDP when running at the base clock. What's happening when your laptop goes briefly to 4.2 GHz is that it exceeds both the Intel-stated TDP and the cooling system TDP. Then it throttles back to 3.2 GHz, which is a little below the cooling system TDP but above the processor TDP. In a laptop like the XPS 15, the cooling system TDP is only a little higher than Intel-stated TDP. The momentary thermal headroom between what the CPU puts out at max Turbo and the cooling system TDP is provided by the heat capacity of the metal in the heatsink/heatpipe.

karolist 7y ago

My Lenovo W530 still has a socketed CPU which I've replaced from 2 core/4 thread i5-3210M to 4 core/8 thread i7-3610QM and it will happily chug along without down throttling in parallel compilation, benchmarks or games using eGPU. It's a 45W TDP CPU and there are stronger ones doing fine still. And before you say "that's outdated" - well not really https://browser.geekbench.com/processors/753 https://browser.geekbench.com/processors/753, it's about as fast per core as 2013 retina MBP and has 4 real cores. I guess my point is "you can make it work". Now, my work's 2018 15" MBP is suffering massive overheating problems and throttling down just on some light work + YouTube.