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I would just like to quickly add that I think the really critical piece for using dual-core processors is the optimizing software. Is it sequential or can it do a variety of runs all at the same time? I know that TRNSYS has been used with a variety of “multi-run” tools such as Condor that send out many runs of a software to many different computers. However, this only works if the process is able to be parallelized (like in a monte-carlo analysis). If the tool requires that the results of each run be analyzed before the next run is initiated, then it must be sequential unfortunately.
I’ve also found that a dual-core is helpful with many TRNSYS runs because you can still use the “other core” for other tasks such as email, Excel, etc. while TRNSYS works along in the background.
I’m still waiting for a 4 Ghz machine myself.
From:
trnsys-users-bounces@engr.wisc.edu [mailto:trnsys-users-bounces@engr.wisc.edu] On Behalf Of Janne Paavilainen
Hi!
OK, as you can see from the replies it's quite a messy jungle with PCs nowadays. I've also been a few times in the position of trying to justify the needs/benefits of a new work-station for simulations (not only TRNSYS) and it's not always easy. Your interest in reducing sim time is understandable as with your current setting you end up easily in >24hr simulation times (thousands of 100sec sims).
Trying to summarize some guide-lines from previous mails:
* If you have an older generation CPU, then upgrading to a good PC of the current CPU generation will probably already halve your simulation time, give or take. This you can see e.g. from Rafs test, or comparing bench-mark results on net reviews.
* If you already have a PC with a current generation CPU, then you have to start thinking about price vs. performance. Getting a 20-30% CPU performance boost (sim time reduction) compared to good standard PCs might almost double the price of your new work-station, this might be difficult to justify.
* Also, looking at the previous point: If you can divide your problem into two, buying e.g. two good standard PCs instead one of the fastest possible, might almost halve your total sim time instead of the 20-30% reduction for one simulation for the same price. And after the project you have two perfectly good PCs to give to new employees, instead of one.
* The benefit of a dual-core CPU is harder to comment on. You might be able to do with one PC the same as with two computers as described above, but it would be better to test it before buying. This is possible at least with TRNSYS-only, but it might be more complicated in combination with other programs. You should be able to test this with a single core CPU, on your current PC (the simulation will be a crawl, but at least you should be able to see if it works).
* Running two simultaneous simulations on dual-core generates a lot of heat, take care that the cooling of the PC is well done. If you are running simulations of several hours like this, you might end up crashing your hard disk in no-time because of the elevated operating temperature. This problem is not over-exaggerated!!!
* With a dual core CPU you can work normally while a TRNSYS simulation is running in the background at full speed. This wasn't possible with single core CPUs.
* RAM isn't an issue with TRNSYS, anything above 1GB is overkill, unless you are using other software which need more (actually, already 1GB is overkill, if only for TRNSYS+OS).
* Hard disk isn't an issue either, modern HD:s can handle about any amount of data that TRNSYS itself has to read and can spit out. (Unless you are doing something else that's HD intensive at the same time)
A suggestion to TRNSYS development group: It might be a good idea to have some general guide-lines about this on the TRNSYS home pages in addition to the general hardware requirements/recommendations. Generally, when a new project involving simulations is started, almost always the need for a new computer is discussed in the first meeting. The "Hardware requirements" section in the manual does not give much help considering e.g. Rémis problem. This might easily lead to "buying overkill" or spending money on the wrong part of the hardware. And trying to google the www you end up spendings various hours reading and still not knowing which way you should go.
Regards Janne
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