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-   -   Desktop upgrade or new laptop? (http://www.cfd-online.com/Forums/hardware/94056-desktop-upgrade-new-laptop.html)

farshadn12 November 4, 2011 00:04

Desktop upgrade or new laptop?
 
Hi everyone!

I'm about to start a project which will include flow/heat transfer simulations of a 3D domain with about 5.4 million cells in FLUENT. I have a desktop computer with the following specs:

- 2.9 Ghz Dual core AMD CPU with 2MB of cache
- 1 GB of DDR2 RAM, 667Mhz

Now I have two options here. Either buy up to 16GB of DDR2 1066Mhz RAM and use the same system (this sounds extremely efficient budget-wise) or buy a brand new laptop. I'm thinking 3600, 0.25sec time steps and a total of 5-6 simulations. I have 5-6 months to do the project. Can anyone work up an estimate?

Anyway, what should I do? And generally speaking, since I'll have to keep the system running for 6-7 days straight, do you recommend a laptop at all? Can these machines take the strain?? o

abdul099 November 5, 2011 17:12

Honestly, your desktop is not worth to upgrade. The only good thing doing this would be the low cost (memory costs nearly nothing).

A laptop would be good regarding power consumption and a new laptop has the potential to be much faster than your old desktop system.
Anyway, laptops have some deficiencies in cooling. The small case, bad air flow etc. is not good and also the battery will not like to stay in the hot case for days or weeks.

So my recommendation would be to go for a new desktop system. You will not need a high-end system, therefore the cost could be lower than a new laptop (or at the same level for a more powerful machine).

I'm not aware how Fluent performs, but supposing it's comparable to other codes, you should end up working way before hitting the time frame. I did about 20 simulations with 35M cells in 2.5 months on 3 dualcore workstations, including shutdown periodes, meshing, postprocessing etc.

farshadn12 November 6, 2011 12:38

Quote:

Originally Posted by abdul099 (Post 330877)
Honestly, your desktop is not worth to upgrade. The only good thing doing this would be the low cost (memory costs nearly nothing).

A laptop would be good regarding power consumption and a new laptop has the potential to be much faster than your old desktop system.
Anyway, laptops have some deficiencies in cooling. The small case, bad air flow etc. is not good and also the battery will not like to stay in the hot case for days or weeks.

So my recommendation would be to go for a new desktop system. You will not need a high-end system, therefore the cost could be lower than a new laptop (or at the same level for a more powerful machine).

I'm not aware how Fluent performs, but supposing it's comparable to other codes, you should end up working way before hitting the time frame. I did about 20 simulations with 35M cells in 2.5 months on 3 dualcore workstations, including shutdown periodes, meshing, postprocessing etc.

Thank you for your reply. I guess I'll add more ram to the old desktop (won't cost that much) and switch to 64 bit windows and see what happens. I'll dedicate this system to simulations completely (no other software on the machine whatsoever). Trouble is, my fluent license allows for up to two cores, any more parallel computing and I'll have to update my license which is costly. So I guess buying a new desktop won't make a huge difference. Since it seems that I have enough time to complete the project, I'll also buy a new, powerful laptop to complement the whole thing.

abdul099 November 11, 2011 16:20

Well, a new system could be much faster than your current one, even when running only on two cores. But it depends much on your old system and the "virtual new one we suppose to be existent for this post".
For example a Xeon X5550, 2,66GHz based on Nehalem architecture is twice as fast as a Xeon E5440, 2,83GHz based on Core2 architecture, running the same code, same simulation etc.
But I understand the cost doesn't make it that attractive, especially when running on only two cores.

On the other hand, when using only two cores, the heat production of the CPU is much lower than running on four cores. Assuming, you would buy a decent quad core laptop, which is currently an i7 (I'm sorry I have to advice an Intel CPU, usually I prefer AMD CPU's - not due to the performance, just due to the cost-performance-ration), it shouldn't cause that much problems.
Running applications with a lot of load on one or two cores is not the problem even on laptops. The problem is just running on all available cores for a longer period.

farshadn12 November 11, 2011 16:35

well I bought the new laptop. You can find the specs here: http://www.asus.com/Notebooks/Multim...specifications

It's the one with the Core i7 2630 CPU.

abdul099 November 13, 2011 20:06

Seems to be a decend one. How much memory did you purchase?

farshadn12 March 5, 2012 02:13

it have 8GB of ram


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