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Re: [TRNSYS-users] PC capacities to run faster?



Hi!

Some guidelines:

In general, it's the combination CPU+Motherboard+RAM that defines the total "speed" of your PC. The key figure here is memory read/write speed, usually given as MB/s. The bottle neck can be any of the three parts of the combination. So be aware that upgrading CPU will do no good if the MoBo bus or the RAM turn into bottle necks.

CPU and motherboard
As fast as your budget allows, direct relation between CPU speed and simulation time. TRNSYS16 does not have multi-core support. However, you can run e.g. two simultaneous simulations on a dual core CPU halving the total needed time if the simulations are independent (i.e. if you don't have to wait for the results of one to start the other). Dual core is also useful if you need to use the work station for normal use when the simulation is running. I'd guess you can run 4 simultaneous simulations in a quad core, but I never tested that. Also don't know if the time divider will really be 4 or less in that case.

RAM
TRNSYS is no memory hog, usually a model takes up memory in the order of a few MB to tens of MB. So if you don't have any other memory eating software connected to your TRNSYS model this is not an issue. But... be aware that memory speed can be a bottle neck, you have to carefully match your RAM to the CPU and mother board bus speeds if you want to optimize PC performance.

HD
Hard disk should not be a bottle neck. Even if it seems that during a simulation the HD light is blinking all the time, the real HD idle time is probably >95%. If you're producing output files in the order of tens of MB (or even some hundreds of MB) for a long sim you should have no worries.

Cooling
TRNSYS sucks up to the CPU 100% producing a lot of heat when your simulation takes hours. You have to take care of cooling not to burn the CPU or destroy your hard disks. If you plan to run simultaneous simulations on multi-core I would monitor the computer temperatures on a test run to be sure that the cooling is sufficient before leaving the machine running for hours by its own. If it's in a small room, leave it ventilated.


Cheers
Janne

PS. When I built my home recording studio PC about 1.5 years ago, the Intel CPU were using a lot less electricity and thus also producing a lot less heat than the AMD processors. Don't know if that's changed. PS2. You can get fast computers from e.g. Dell but they cost a lot more than building it yourself. On the other hand, building a fast PC from scratch, choosing components and getting it running (and eventual overclocking) may be very time consuming (days...) and you have little/no support when you run in to trouble. I would not be able to justify building a PC on my work time. PS3. Check your current PC benchmark (memory read/write) with some free software and compare performance to new CPUs (within your budget range) somewhere on the net, so that your not ending up wasting a lot of money and time for e.g. 20% shorter simulation time. PS4. Overclocking forums on the www are good info sources if you plan to build the PC yourself.

--
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Janne Paavilainen MSc, Doktorand
Forskare inom Energi och miljöteknik
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Solar Energy Research Center SERC
Högskolan Dalarna
SE-781 88 Borlänge
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tel +46 (0)23 778728
fax +46 (0)23 778701
e-mail: jip@du.se
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www.du.se
www.serc.se
www.eses.org
www.uni-kassel.de/fb15/ite/solar/solnet/
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Francois wrote:

Hi all,

I am running a simulation with TRNSYS that takes almost 24h because of a heavy component and a small timestep. I don't want to have to change my parameters because I need accurate results.

Currently, I have got a DELL PC with an Intel Pentium 2GHz and a RAM of 1GB.

I am willing to upgrade to a new computer running maybe 3 or 4 time faster...

Could somebody tell me what equipment would be worth to buy, or even what kind of processor and memory should I consider?

Thanks for some help.

Francois

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