Is this Intel i7 machine good for LTSpice?

Folks,

Need to spiff up my simulation speeds here. IIRC Mike Engelhardt stated that the Intel i7 is a really good processor for LTSPice. According to this it looks like the 4790 is the fastest of the bunch:

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So, what do thee say, is the computer in the Costco link below a good deal for LTSpice purposes?

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It's also available without MS-Office Home & Student 2013 for $100 less but I found that OpenOffice isn't 100% compatible in the Excel area so that sounds like an ok deal. My hope is that it can drive two 27" monitors but I guess I can always add in another graphics card if not.

Reason I am looking at these is that I absolutely positively do not want any computer with Windows 8 in here and unfortunately that's what many others come with.

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Joerg
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Don't know about computation speed, but this link says the video card will drive 3 monitors:

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Looking at Dell's site I don't see any mention of expansion slots, and looking at the one picture with the cover off I really can't see any sockets beyond the video card, so if any further expansion is important you need to ask Dell for clarification.

Folks,

Need to spiff up my simulation speeds here. IIRC Mike Engelhardt stated that the Intel i7 is a really good processor for LTSPice. According to this it looks like the 4790 is the fastest of the bunch:

formatting link

So, what do thee say, is the computer in the Costco link below a good deal for LTSpice purposes?

formatting link

It's also available without MS-Office Home & Student 2013 for $100 less but I found that OpenOffice isn't 100% compatible in the Excel area so that sounds like an ok deal. My hope is that it can drive two 27" monitors but I guess I can always add in another graphics card if not.

Reason I am looking at these is that I absolutely positively do not want any computer with Windows 8 in here and unfortunately that's what many others come with.

--
Regards, Joerg 

http://www.analogconsultants.com/
Reply to
Carl Ijames

I have spent too many hours this weekend tweaking the transient response of a semi-hysteretic (we call it "hysterical") switchmode constant-current source. There are about 8 interacting knobs to turn. At 30 seconds per run, understanding the interactions is impossible.

I want sliders on each of the part values, and I want to see the waveforms change as I move the sliders, like they were trimpots on a breadboard and I was looking at a scope. I need maybe 500 times the compute power that I have now.

Mike should code LT Spice to execute on a high-end video card.

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John Larkin         Highland Technology, Inc 

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John Larkin

You can go quite a bit faster with a nice multicore machine--LTspice lets you choose how many threads to run. My desktop machine (about 3 years old now) runs about 150 Gflops peak. Supermicro is an excellent vendor.

Cheers

Phil Hobbs

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Dr Philip C D Hobbs 
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Phil Hobbs

On a sunny day (Sun, 02 Nov 2014 08:00:36 -0800) it happened John Larkin wrote in :

Maybe building the real thing with some pots? But without some theory backing it up how would you know it always works? And with the theory you do not need the sliders.

I do not see the need for insane speeds, I have used LTspice more than often the last few days, running on an old Duron 950, fast enough. maybe you guys are doing something wrong? :-)

And it is always an approximation, build the real thing too, needed tweaking with resistors in series, that is analog, got some nice 25 turn Bourns trimpots from ebay.....

Reply to
Jan Panteltje

Looks like you are right:

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Quote "There?s only one PCIe x16 slot, which means you won?t be able to add a second video card to take advantage of Nvidia?s SLI technology".

No slots. There's one more card in the bottom, not sure what that is. But if the video can drive three monitors it should be fine, I never added any cards to my current PC either.

[...]
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Regards, Joerg 

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Reply to
Joerg

Only question is, how can one connect two regular OPC monitors to this?

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Regards, Joerg 

http://www.analogconsultants.com/
Reply to
Joerg

That's exactly why I need all the speed I can get.

I use the .STEP command a lot, sometimes nested. Then I get multiple sets of curve sets. But often I have to start it at night and see the results the next morning. The nice thing in winter is that this pre-heats the office.

There are so many variants of graphics cards that it would require tons of work for Mike's team.

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Regards, Joerg 

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Reply to
Joerg

But they should work on their web site some more or get rid of scripting or whatever. Other than a language selector it shows ... nothing.

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Regards, Joerg 

http://www.analogconsultants.com/
Reply to
Joerg

[snip]

Mostly I only use LTspice to run other's schematics or to run netlists generated by PSpice, but I'd hazard a guess...

Either via .STEP or saving and superimposing data files I'm sure you can generate a family of curves versus your knob twisting (though I might make the argument that, if you "design" by knob twisting, you're not much of a designer >:-}

Here's a trick I picked up a few years ago that allows tons of data runs to be collected into a single postscript file:

Concatenate the following...

header.ps yourfile1.ps yourfile2.ps yourfile3.ps yourfile4.ps | | footer.ps

The result superimposes all your data runs into one postscript file graph. (I then run the result thru Adobe Acrobat to convert to a PDF.)

Here are the files you need....

header.ps:

%% %% First things first, we set up the letter tray. Of course %% if you wnated another tray, you could change this... %% [{ %%BeginFeature: *PageSize Letter statusdict /lettertray get exec %%EndFeature } stopped cleartomark

%% %% Windows drivers stick a 'control-d' at the end of jobs. This causes %% many interpreters to think its the end of job (hang over from serial %% communication days). So, we define an operator called /4 which does %% nothing. %% (\004) cvn {} bind def

%% %% lettertray does different things on different interpeters. On Jaws %% it just changesd the page size, on Adobe it seems to erase the page %% too. Since we've already set it up once, its safe to zap the %% definition. %% statusdict begin /lettertray {} bind def end

%% %% Now we store the *original* definitions of the operators we are %% about to change, in case we need them... %% /Mysetpagedevice /setpagedevice load def /Myshowpage /showpage load def

%% %% Now, we make sure that the job can't change our setup, which might %% cause graphics state resets and other embarrasments. %% /setpagedevice {pop} bind def

%% %% we redefine showpage so that it does nothing, this means that the %% next 'page' will overlay the current page. %% /showpage {} bind def

footer.ps:

%% %% Lastly we emit the *original* showpage definition to 'show' the page %% Myshowpage

...Jim Thompson

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| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
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Reply to
Jim Thompson

There's a setting for one or two threads. Is that all?

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John Larkin         Highland Technology, Inc 

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John Larkin

LTspice benchmark on various machines:

Windoze 8.1 can be made semi-tolerable by putting the start menu back in and making it look like Windoze 7. I've been installing it on all my customers Windoze 8.1 machines and have had no complaints or problems. If you like wiggly icons on the Windoze 8.1 start screen, you can do .

The damage control version of Windoze 10, that is possibly due some time in the distant future, restores the start menu: but otherwise currently looks like Windoze 8.1.

Incidentally, Halloween was the last day that Microsoft will ship Windoze 7 licenses to OEM's.

The Dell XPS 8700 seems like a nice machine. However, if you want performance, I suggest you look at an SSD drive for the OS. I've had good luck with Samsung 840 EVO series drives (mostly 250GB). The ritual is simple. I use Acronis True Image 2014 (not 2015) to clone the hard disk to the SSD. I then replace the hard disk with the SSD and test everything. When done, I wipe the hard disk, and install it as a 2nd hard disk. If I need to return everything to stock, I have the Acronis True Image 2014 backup image with which to recover the initial installation. Elapsed time on a typical fast system is about 1 hr.

Before buying anything, I suggest you try LTspice on the new machine. This is VERY easy with LTspice which doesn't use the registry or require admin rights. Just copy the files to a flash drive and it should work.

One catch. LTspice saves its preferences to: C:\windows\scad3.ini which has to be writeable. The fix is to use the -ini command line switch, which will: Specify an .ini file to use other than %WINDIR%\scad3.ini

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Jeff Liebermann     jeffl@cruzio.com 
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Jeff Liebermann

Too much risk. I've heard that running legacy software is tough in Win-8 but Win-7 can mostly do it. Not as good as XP.

Any guess how long MS will support Win-7?

When it comes to PCs I am lazy :-)

I just want to plug it in and go. Re-installing all my stuff takes enough time already.

I am quite sure Costco will not let me do this :-)

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Regards, Joerg 

http://www.analogconsultants.com/
Reply to
Joerg

I have a two year old laptop. I was tired with the slow startup of programs, so I replaced the hard disk with a SSD. Amazing difference in speed. As far as I can see also for the simulations although I did not do a benchmark test.

The Kingston SSD came with a USB connected enclosure to mount the old hard disk in, so the harrdisk was mirrored and no re install of programs was needed

Cheers

Klaus

Reply to
Klaus Kragelund

That's because you only have two cores. Mine goes up to 15.

Cheers

Phil Hobbs

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Dr Philip C D Hobbs 
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Reply to
Phil Hobbs

Probably a NoScript issue, or something like that. Talk to Alexander at alvio.com a primo Supermicro reseller, and tell him "Hi" from me.

Cheers

Phil Hobbs

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Phil Hobbs

I am halfway through building a breadboard; I'll post pics. I'm after extreme broadband high impedance output, which is hard to measure on a breadboard; Spice lets me graph all sorts of currents and nodes, so it's the best platform for development.

I'll have to simulate, and then test, the thing over a range of loads.

I don't have sufficient theoretical skills to tune this circuit. I'm not sure if anyone does.

At 30-50 seconds per run, iteration is slow. Worse, the time lag wrecks my ability to acquire intuition about what's going on.

I'll have to tweak resistors and capacitors, and the cap values are too big for variable capacitors. And, as noted, it would be hard to instrument.

Here's the current output when the load voltage steps from about 0.5 to 3 volts.

I want it as flat as possible.

The fast ripple is the basic 1.5 MHz switcher frequency. The various whoopie-doos are from loop dynamics and the chain of progressively smaller, bias-tee-like damped inductors between the switcher and the load. The constant-current hysterical switcher is, natively, about 4 or so orders of magnitude too slow for my application.

Everything interacts with everything else; it's like tuning a big LC filter by hand, never a fun thing to do. Spice helps me acquire at least some instincts for tuning. Maybe I can fix the cap values and tune only resistors on the breadboard.

Rob, one of my guys, has a fierce Linux computer just for sims and FPGA compiles, and he knows how to do automatic iterative parts value tweaking in a loop around Spice. Maybe he can set up the problem and run it for a couple of days or weeks.

I could probably step each of the six most important values, maybe 4 steps each, and pick the best waveform. That would be 4096 sims, about

60 hours of computing on my PC.
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John Larkin         Highland Technology, Inc 

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Reply to
John Larkin

Just pick one of the Nvidia number cruncher monsters. There are C compilers available.

You can buy an Nvidia "video" board with no video out; it's just a 200 or something core compute engine.

Maybe the SuperSpice guy is interested. There's money there.

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John Larkin         Highland Technology, Inc 

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Reply to
John Larkin

Looks pretty decent for the money, 32G is a sensible amount of RAM- the RAM speed might be a bit on the low side though. I only research this stuff when I'm shopping for a new box, but that stands out.

You can get a 1T Samsung SSD for only about $450, which allows you to leave the mechanical one it comes with (worth < $100) pristine and to be returned with the computer if necessary (so no proprietary information can escape).

Best regards, Spehro Pefhany

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Spehro Pefhany

You can do that in Multisim, but it's single thread only, no faster than any other simulator.

Tim

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Tim Williams

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