Pentium 4 D 2.66Ghz
 

Hi
I haven't found Pentium 4 D 2.66Ghz on the bench page.
I'm planning to buy one (it costs less than half of the price of a P4 3.6Ghz) and I have some questions.
-Is [[B]Intel Pentium D[/B] 805 [B]2.66GHz[/B], S775,[B] 2x1Mb L2[/B], FSB533, Smithfield] better than [[B]Intel Pentium 4[/B] 631 [B]3.0GHz[/B], S775,[B] 2Mb L2[/B], FSB800, Prescott]?
-P4 631 supports HyperThreading, P4D 805 doesn't. P4D has two core, right? If both allow to run 2 instances of mprime, what should I choose?
-Any advice are welcome :)

Some more information :
I'm willing to buy [URL="http://www.aware.ch/asus-p5vd1x-p-1930.html"]this motherboard[/URL] with, with [URL="http://www.aware.ch/512mb-pc3200-p-423.html"]512Mo RAM[/URL], [URL="http://www.aware.ch/350w-swisscase-24pin-p-18.html"]alim[/URL], and one of these proc : [URL="http://www.aware.ch/intel-pentium-p-1858.html"]P4 3.0Ghz[/URL] or [URL="http://www.aware.ch/intel-pentium-p-1880.html"]P4D 2.66Ghz[/URL].

This box will run 24/7/365, with gentoo gnu/linux or freebsd, more probably gentoo.

Thanks

Without a shadow of a doubt, go for the dual core. Prime95 is so optimised that it can't take much advantage of HT.

Ok, thanks. So the best is the cheapest. Interresting.
Another good link : [url]http://www.anandtech.com/cpuchipsets/showdoc.aspx?i=2736&p=1[/url]

Well, another point : "Prime95 is so optimised that it can't take much advantage of HT." And for some other project like Riesel Search?
hmmm, 1 core for llr, the other for mprime :)

[QUOTE=victor]Well, another point : "Prime95 is so optimised that it can't take much advantage of HT." And for some other project like Riesel Search?
hmmm, 1 core for llr, the other for mprime :)[/QUOTE]

Fortunately, llr and mprime shares a lot of code -- so the situation doesn't change... much. However, different applications might behave differently. However, HT is expected to give a thruput improvement of roughly 30% for random applications -- obviously, the actual improvement would be much less for mprime and llr. With the dual core, you should expect to get atleast an 80% improvement in thruput (80% is a SWAG -- but I see nearly 95% improvement in thruput for my Pentium D 820, 2.8G 800MHz FSB while running llr).

I just built a 805 D on an Asus mainboard and got it overclocked by 10% -- the thing runs hot resulting in the case side having to be removed to stop the fan from screaming. They're a real bargain at the moment... :love:

I only got XP home 32-bit which worked with the same disk I had in the box before -- it required reactivation. I've got SMP 32-bit Mandrake 10.2 on it too but will put 64-bit Ubuntu on it very soon ...

The 805 seems to be really good at overclocking : [url]http://www.pctuner.net/php/Articoli/Articolo.php?PAG=4&id=393&access=&lang=eng[/url]
:D
6Ghz with liquid nitrogen cooling!

Paul, can I ask you which model is your mainboard?

axn1 > Many thanks for your reply!

[QUOTE]Paul, can I ask you which model is your mainboard?[/QUOTE]

Asus P5VD1-X. It's a VIA chipset. It's very veristile with plug-in graphics cards. Good FSB range. Uses DDR memory, not DDR2. :cool:

edit: I see that's the one of your choice. I'd go for two sticks of RAM for dual channel mode. I put a 550W supply in it -- for overclocking and AGP...

FYI: I've read the 805D is not a hyperthreading supported chip. However, make sure you have hyperthreading switched on in BIOS, or else you'll notice a halving of throughput -- I found out the hard way :furious:

[QUOTE=paulunderwood]FYI: I've read the 805D is not a hyperthreading supported chip. However, make sure you have hyperthreading switched on in BIOS, or else you'll notice a halving of throughput -- I found out the hard way :furious:[/QUOTE]
AFAIK, none of the dual cores are HT enabled (with the exception of an Extreme Edition version). Did you mean "switch on 'dual core' in BIOS?"

On the [URL="http://en.wikipedia.org/wiki/Pentium_D"]Wiki page[/URL] it states "[I]The Smithfield Pentium D does not support Hyper-Threading, at least initially, although similar Extreme Edition counterparts do.[/I]". I had a hyperthreading switch in BIOS for the Asus board which I switched off! But then I was only getting half the throughput. This morning I realized my mistake and switched back on hyperthreading and all is good. I also got it clocked a 3.0GHz and it is mprime-stable.

I built a case-less system to run Prime95 exclusively, and it was a PD 805 with an ASUS P5V800-MX, and I couldn't overclock that thing at all. The oc'ing options in the mobo were very limited - no settings to tweak vcore or vdimm. Basically, just options to change the frequency on the FSB, plus change the memory timings. I got errors running PRIME95, overclocked even just 1 Mhz. The P5VD1-X you used - does it have more oc'ing options than what I've described on the P5V800-MX?

My interest is to build dual-core systems as cheaply as possible to run Prime95 - the cheaper they are, the more I can build. I had considered paying a bit more for better motherboards with the intent of getting at least 15% ocs.