RE: Mersenne: M#40 - what went wrong?

[Brandon Gale]

> -Original Message-
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] Behalf Of John R
> Pierce
> Sent: Friday, June 13, 2003 6:42 PM
> To: Aaron Lehmann; Mersenne discussion list
> Subject: Re: Mersenne: M#40 - what went wrong?
> 
> 
> > On Fri, Jun 13, 2003 at 03:16:24PM -0400, George Woltman wrote:
> > > 2) This case results from the way my C compiler treats floating point
> NaN.
> > > NaN stands for not a number. If NaN is converted to an integer, the
> integer
> > > is zero. So if the FFT data is all NaNs, prime95 will report a prime.
> >
> > I expect this is a FAQ and apologize in advance, but in the age of
> > SSE2 integer instructions why is it still necessary to use floating
> > point calculations?
> 
> precision.
> 
> The extended FP multiply has 64 bits of mantissa.   SSE2 is, I believe,
> restricted to 32bit multiplies, so it would take 4 times as many to equal
> one 64bit  (gross simplification, but sufficient for the purposes here).

Is that still true on the 64-bit platforms (ia64 and amd64)?

Brandon

> 
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RE: Mersenne: please recommend a machine

[Brandon Gale]

I found this article to be helpful -
http://www.hardcoreware.net/reviews/review-118-1.htm

But, be prepared to shell out some doh.

Thanks,
brandon

> -Original Message-
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] Behalf Of Steinar H.
> Gunderson
> Sent: Saturday, March 08, 2003 7:49 AM
> To: [EMAIL PROTECTED]
> Subject: Re: Mersenne: please recommend a machine
>
>
> On Sat, Mar 08, 2003 at 09:11:38AM +, Brian J. Beesley wrote:
> > You _might_ be able to recycle the old case as well - however you will
> > probably need to replace the PSU with a new one in order to
> supply the power
> > requirements of a P4 system. Look for PSUs rated over 300W with
> dual fans - I
> > particularly reccomend the Enermax PSU with rheostat fan speed control
> > because it's quiet & effective, though certainly not cheap.
>
> While we're at it -- is it possible nowadays to get power
> supplies _without_
> fans, or at least with only one? I removed my (rather noisy) SCSI disks a
> month or so ago in favour of running diskless over NFS (unfortunately, I
> can't get the gigabit cabling to work, so it's `only' 100mbit
> ATM), so what I
> have left of fans is:
>
>   - One 12dB CPU fan (80mm -- it used to be a problem that the
> CPU got hot,
> think 85°C, but after getting a proper heat sink it rarely
> goes over 60°C)
>   - One microscopic fan on the graphics card
>   - The two power supply fans (one 80mm and one 120mm)
>
> It's funny -- when the disks and the CPU cooler noise goes away,
> you suddenly
> start to care about the power supply, even though it is rather
> quiet already.
> As I barely have any equipment left in the PC anymore (an Athlon XP 1700+,
> some RAM, two rather old graphics cards, a network card and a
> sound card) I
> don't think I'm going to need very much power either... Anybody
> know what my
> options are if I want a silent power supply? :-)
>
> /* Steinar */
> --
> Homepage: http://www.sesse.net/
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