which Windows OS is best for IVF 10.0?

[noheat]

To get more speed, I'm ordering some new PCs and IVF 10.0 to replace Compaq Visual Fortran on Windows XP machines. We do scientific number crunching, with simple codes that run for days doing repetitive arithmetic and simple I/O to files.

I'm hoping to learn which Windows OS is best for IVF 10.0. Dell offers me a choice of four operating systems with the Core2 Duo PC I'm considering buying for <$1k:
XP Professional, SP2, x32
XP Professional, SP2, x64
Windows Vista Business, 32 Edition
Windows Vista Ultimate, 32 Edition

Which should I choose, if number crunching will be my only use of the PC?

[Steven_L_Intel1]

Of those, I would recommend the XP x64. I think you'll benefit from the 64-bit environment. If they offered Vista 64-bit, that would be a fine choice too.

IVF itself really doesn't care, so the question is what's best for your application.

[noheat]

Thanks, Steve

[jimdempseyatthecove]

Noheat,

A lot will depend on your application.

In general though - applications is x64 have more working registers and therefore (with an optimizing compiler) tend to run faster. So unless you consider a Vista x64 I would expect that XP SP2 x64 would run faster. You might also see if they have a WindowsServer2003 x64. I cannot say for sure about the performance difference (if any) between XPx64 and Server 2003x64. I use Server 2003x64 but have not been able to compare with XPx64. The code will be the same - the O/S overhead will be different.

Also. If your number crunching is displaying a status display with frequent updating then replace the on-board video with a cheap video card.

Jim Dempsey

[noheat]

So it is possible that a code compiled by IVF will run faster with 64-bit Windows than with 32-bit Windows?

[Steven_L_Intel1]

Possible? Sure. As noted, there are more integer and address registers available which can improve performance. The actual arithmetic should be pretty much the same. However, if you have lots of address-sized things (less likely in Fortran than C), the added size can increase memory traffic.

But the real advantage of 64-bit is that you don't have to worry about your problem size getting too big for the hardware.

The disadvantage is that if you buy separate hardware, you may have a harder time finding drivers for it. This won't be an issue with a system configured by Dell, and a lot of vendors are doing a good job on 64-bit drivers overall, so I would not let it stop you unless you insist on using some old peripheral whose vendor went out of business years ago.