Running HEC-RAS on laptop with Intel turbo boost processor

[Anonymous]

I am in the market for a new laptop. I’m also a graduate student so my budget is limited. I want to be able to have decent performance for running large 2D HEC-RAS models and have ArcGIS run smoothly (specs say it requires processor with 2.2 GHz quad core. I’m looking at Lenovo PCs with Windows 10 and seeking advice about what is the minimum speed processor I need to buy (all the models I’m considering have at least 16GB RAM, SSD drive, good graphics, etc. so the only outstanding variable is the CPU). Several models have Intel Core i7 with 4 cores and a base processing frequency of 1.9 GHz and turbo boost frequency up to 3.5 or 4 GHz, while other more expensive models have 6 core 2.2 to 2.6 GHz base and turbo boost up to 4.1 to 4.6 GHz. Will these computers actually run for a few hours at a time at speeds that are above the base frequency, ideally close to the max of the turbo boost range so that I might purchase a less expensive model with a 1.9 GHz base and still get fast run time with HEC-RAS, ArcGIS and other processor heavy software? If anyone has had experience running HEC-RAS on a laptop with this type of Intel processor, I would really appreciate input before I buy. Having a very hard time geting clear info from anywhere else.
Thank you

[Scott Miller]

Chris wrote up a blog post on this. A good starting point.

My first tip is to avoid the laptop if you’re doing 2D modeling. My employer supplied me with a Dell Precision 5510 laptop with a 4-core Core i7-6820HQ processor, 2.7 GHz base speed with 3.6 GHz turbo. It’s comparable to the chip you mentioned. That turbo speed does not necessarily apply to all of the cores, maybe just one. But the real issue is heat management.

When I started 2D modeling last year I was using this laptop. It is set on top of an overturned wire inbox basket, so cooling is all about the laptop design. The fan would jet frequently, with processing speed taking a dive as the machine tried to keep the processor from overheating. Putting an ice pack on the laptop helped, but was not a practical solution. This laptop would crank through the model, sure enough, but it was very, very slow with the processor diving off. I didn’t have several months to run model scenarios, and there was wear and tear on the laptop to consider.

I ended doing the research and building a fast computer in a medium chassis with proper cooling. Any tower type computer with good ventilation would probably be better than a laptop. Over time, wear and tear on your laptop cooling system, degradation of the memory (which probably won’t have heat sensors), and possibly degradation of the processor will shorten the life cycle of your laptop. (You could consider leasing!)

If it has to be a laptop, your best bet for 2D HEC RAS modeling would probably be a huge gaming laptop with the processor of your choice, but those aren’t exactly budget computers.

[Anonymous]

Thanks very much Scott. This is very helpful information. Given that I’m in the market first and foremost for a fairly portable laptop, not a big heavy duty gaming one, I guess the issue boils down to having a machine that will do a decent job of running a 2D model, but only depending on it occasionally and otherwise using a desktop.

Am I correct in reading your response that the turbo boost processor does kick in. It just isn’t sustainable because the computer gets too hot?

Do you know if there’s any way to tell from the computer specs whether the turbo boost applies to all cores? That seems like false advertising if it doesn’t and would mean that it’s even more important to have faster base processing speed for the cores that don’t increase to turbo.

Good point about the long term wear and tear overall.

Thank you!

[Scott Miller]

My read on it is that a processor with Turbo Boost has a design power consumption and a safe clock speed. The base clock speed is what all cores can operate at simultaneously. If there is computational demand for a higher clock speed, and the temperature is not too high, Turbo Boost will kick in. Now, if it is a single thread demand, then that core can operate up to the design power consumption, which would give you the Turbo Boost speed.

But… 1. If it is a multi-thread demand, the design power consumption will be spread across the cores that make the demand, and their clock speed will be some fraction of the Turbo Boost speed – They’ll get some fractional increase. 2. If the processor gets too hot, the BIOS will protect it by reducing the clock speed.

My laptop was multi-threading HEC RAS and getting clock speed dive because the BIOS was protecting the processor. My understanding is that, unless I am overclocking the processor, the processor will degrade last. Wear and tear on the cooling system and thermal degradation of the memory cards happen first, as hardware goes. And protecting the processor slows down the model.

My work laptop, the Dell Precision, has a slim form factor. It is designed to be thin in the race to be the thinnest, rather than being designed for performance. It doesn’t even have a LAN port, since it has WiFi. I recommend that if you must get a laptop that will be used for 2D modeling, make sure it is designed for heavy computation. Make sure it has the best cooling system possible within your budget.

Another route you can take is cloud computing. In order to keep your laptop running well through its life cycle, outsource the computation. You can try different virtual processors to get the model speed you need, and let your model run whether your laptop is on or off.

[AHP]

I am a former USACE employee. I have run reasonably large 2-D models on a Precision M6600, but the specs have to be through the roof. I don’t remember what my exact specs were, but the current standard issue machine for science and engineering is the Precision 7760 with a Xeon 11955M, which starts at $5000. Add on a sufficient SSD and RAM and you are easily over $7000.

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