How do I select an upgrade processor chip?

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I have a Dell Dimension 4550 2GHZ XP system that I want to use
with a tuner for HDTV.
It almost works, but the CPU usage is nearly 100% so the keyboard/mouse
don't respond well.
No problem, I'll just upgrade to a faster processor.
I'm looking for the biggest bang for the buck.
I'm an electrical engineer. I thought I understood
clocks and busses and multipliers. But the more I look,
the confuseder I get. Processors come in many versions
with different clock multiplers and fsb speeds. That relates
somehow to the memory clock, but not in an integer way.

I've been poking around with cpuz, siw.exe and PCWizard 2008
on my Dell 4600 2.4GHz and the 4550 2.0GHz. My PC3200 ram is capable of
400MHz, but running
at 266. The motherboard is capable of a faster FSB than it's set for.

I think I understand the clock/bus/multiplier concepts.
What I don't understand is HOW the motherboard/operating system
decides to set up those numbers? What information is used?
Is the default configuration normally optimum for throughput?
The BIOS has ZERO configuration options in this area.

If I assume that the multiplier is locked, I still have options
of which processor to buy and the resultant multiplier and FSB.

Hypothesis: There's an optimum combination of system clock
and processor multiplier for my system. Installing a faster processor
may cause the memory speed to change resulting in LESS performance.
For PC3200 memory does a CPU clock that's an integer multiple of
400 MHz. result in faster system speed than one that isn't?
Am I better off with a 100MHz FSB, higher multiplier and 400MHz memory
transfer
or 133MHZ FSB, lower multiplier and 266MHz memory transfer?
Or am I just misinterpreting
the numbers?

For decoding video streams, seems like the memory bandwidth
would be the most critical parameter to optimize???

I'm not interested in overclocking or squeezing the last half a percent
out of a benchmark. I want to avoid a big BLUNDER, like...

Buying a processor that won't work at all in my system.
Buying a 2.6GHz processor when a 2.4GHz would have better throughput
and less thermal problems
given the PC3200 RAM.

Current processor is a northwood...sounds like I should stick with that
family???

Google finds me a lot of discussion, but little enlightenment.
Is there a holistic tutorial on the subject?

Thanks, mike
 
Andy said:
According to
<http://support.dell.com/support/edocs/systems/dim4550/specs.htm#1101572>,
Microprocessor type
Intel® Pentium® 4 microprocessor that runs at 1.80, 1.90, 2.0, or 2.20
GHz internally and 400 MHz externally; or 2.26, 2.4, 2.53, 2.66, 2.8,
or 3.06 GHz internally and 533 MHz externally
Click to expand...

Thanks, but that doesn't help my overall understanding of the process.
Part of the problem is that the different diagnostic tools use slightly
different terminology.

Check my math...
The processor tells the motherboard to set the System Clock to
100 or 133 or 200MHz.
The FSB is fixed at 4x or
400 or 533 or 800
The processor speed is the multiplier x the System Clock.
That much seems to be consistent.


My problem is how to understand the memory speed.
Ram speed seems to be unrelated to the ram clock.
Both systems have a pair of matched 1GB DDR400/PC3200 simms.
My dim4600-2.4GHz has a 133MHz system clock and 166 ram clock > DDR333
rating
My dim4550-2.0GHz has a 100MHz system clock and 133 ram clock > DDR266
rating
The clock ratios are different and non-integer.
The numbers for the fastest processor seem to indicate that
it runs with a 200MHz clock, 800MHz FSB, and 200MHz ram clock > DDR400
rating. That's a MUCH better ratio of system clock to ram clock
and I'd guess it has MUCH better performance than other 3GHz
configurations. Yes? No?
Then there's a whole other set of issues when the ram speed rating is
less than optimum. The RAM clock throttles back to what the ram can handle?

I'm completely confused about what determines the memory clock and why
I can't get DDR400 speed out of the ram without a 200MHz system clock.
The ratios are different. If the ram speed is not limiting, shouldn't
the system clock to ram clock be fixed? What determines that?

The 3.06 GHz should be the fastest.
Click to expand...

Ok, but given the memory speed issues, is it a good bang for the buck
and worth the considerably bigger heat load? These things have a passive
heat sink and a low-speed/QUIET processor fan/hood arrangement.
I might be better off to get a 2.8GHz 800MHz fsb for my 4600
and put the 2.4GHz. 533MHz fsb in the 4550...except that the 800MHz
FSB processors seem to have half the cache. And prices will
be all over the map near the high performance end...

And I'm going thru the same issues with a PIII Slot-1 motherboard.
I MUST have the ISA slot, so I'm looking at alternatives for Slot-1
or Socket 370 on a SlotketIII card. More fuzzy issues

I think my head will explode.

I'm not interested in building the fastest possible system.
I want the sweet-spot upgrade that does a good job on HDTV at rational cost.

As the world transitions to multi-core, there will be a lot of older
processors on the fast track to the landfill. I need to understand
how to recognize what I need when I see it.


Shifting gears to the video problem...

I'm using an ATI HDTV Wonder PCI and an ATI 9800Pro Video card.
I have no idea what I'm doing. I tried to run it using windows media,
but the performance was so bad that it's not watchable.
My Dimension 4600 runs vista and WatchHDTV won't work with vista.
It's rumored that there is a beta version that works with vista,
but I can't seem to find it.

So, I've been experimenting with the 4550 and XP or Windows 7,
turns out that WatchHDTV does work in Windows 7. I thought the ATI 9800Pro
had some processing power to bring to the video decoding party, but it
doesn't seem to be any better than my old Radeon 9100. CPU usage sits
right near 100%.

That brings up another thing I don't understand.
How does the cpu% metric work. If the processor is I/O limited
by the memory bandwidth, will it report 100% usage even though
there are unused cpu cycles available? Or will it report lesser
percentage even though it can't keep up with the current video decoding
task.
 
spamme9 machte diesen Vorschlag :
I'm using an ATI HDTV Wonder PCI and an ATI 9800Pro Video card.
I have no idea what I'm doing. I tried to run it using windows media,
but the performance was so bad that it's not watchable.
My Dimension 4600 runs vista and WatchHDTV won't work with vista.
It's rumored that there is a beta version that works with vista,
but I can't seem to find it.

So, I've been experimenting with the 4550 and XP or Windows 7,
turns out that WatchHDTV does work in Windows 7. I thought the ATI 9800Pro
had some processing power to bring to the video decoding party, but it
doesn't seem to be any better than my old Radeon 9100. CPU usage sits
right near 100%.
Click to expand...


I haven't read every line of this thread, so I could've missed if this
was already discussed, but wouldn't the UVD of the newer variants of
the Radeon HD series help?

See here: http://en.wikipedia.org/wiki/UVD

Even if you don't have PCI-E on your motherboard, there are AGP
variants of the Radeon HD 3xxx available.

HTH, O.
 
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