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Gene
Thanks!
1. I am surprised the Athlon 1.3 with DDR is faster than P-4 with
RDRAM--doesn't Rambus RDRAM run at 800 MHz or something, while standard SDRAM
(e.g., PC-133) run at the machine's front-side bus speed (e.g. 133 MHz) -- and
double-data-rate (DDR) RAM run at 2x bus speed?
2. If the access to system memory is the bottleneck (not processor speed), I
would think XEON would be an excellent choice for this reason (particularly if
one gets the 1 MB or 2 MB L1 cache version, vs. the smaller 256K-cached XEON).
If I recall, Xeon's cache runs at full processor speed, too -- unlike the garden
variety P-3's, which runs at bus speed??
3. As I said, I have a 750 MHz Athlon now. I *think* I read somewhere the
newer Athlon Thunderbirds (> 1 GHz) take a Xeon-like approach with the cache,
running it at full processor speed--while Athlons between 750 and 1 Ghz had only
half-speed cache. Have you heard anything along these lines?
ian
Gene Pope wrote:
> Hi Ian,
>
> I was comparing a twin XEON 450 mhz with 500megs and UltraSCSI 3
> vs. 1.3gig Athlon with 500megs DDR memory and Ultra ATA.
>
> That Athlon was 3x faster in computational speed, and at least as fast in
> the hard disk department. And that 3x speed was with a program that is
> "multi-CPU" aware, which TS, and a lot of other financial software, is not,
> which means for TS, the difference is even more graphic.
>
> >From everything I've read from a tech standpoint, the raw speed of the CPU,
> or it's cache size, which between L1, L2 and L3 can be very complicated to
> measure, is NOT the bottleneck in today's systems... it's the access to
> system memory. Most of these fast CPU's are on standby most of the time
> waiting for memory access.
>
> So my approach was, what was the fastest memory/motherboard combo? The
> Athlon / DDR memory appears to be the winner so far. It's why a 1.3 gig
> Athlon can still kick butt with a 1.7gig P4 system with RDRAM, although the
> lead is getting smaller, and for some esoteric functions, the very top P4
> systems are indeed faster. (like MP3 encoding... shucks).
>
> But in our case...i.e. backtesting the snot out of a system as fast as we
> can do it, the single processor is a much better bet.
>
> Hope this helps.
>
> Gene
>
> ----- Original Message -----
> From: "Ian MacAuslan" <imacauslan@xxxxxxxxxx>
> To: <gene@xxxxxxxxxxxxx>
> Sent: Tuesday, June 05, 2001 1:55 PM
> Subject: Re: More than 512MB RAM a benefit?
>
> > Hi Gene
> > Just a followup on your post to Omega List -- I'm considering buying a
> > Xeon machine because of the supposed performance benefit of its larger
> > and faster on-die L-2 cache
> > and I/O benefits vs. a standard P-3.
> >
> > I currently am using a 750 Mhz Athlon. Do I read you right--that the
> > Athlon is way-outperforming your dual-Xeon machine??
> > thanks,
> > Ian
> >
> > Do I read you riught
> >
> > >Running Win2000 on 1.3 gig athlon with 512meg DDR, ultra-ATA100 for
> > some
> > >months now... no problems yet. Next to my older twin Xeon workstation,
> > I see
> > >a 3x speed increase... very happy with speed.
> >
> > >best regards,
> > >Gene
> > --
> >
> > imacauslan@xxxxxxxxxxxx
> >
> >
> >
--
imacauslan@xxxxxxxxxxxx
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