Relationship between Memory Frequency and CPU

mazott

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Hello,

I've recently assembled an Athlon64 AM2 4600+ on a Asus M2N-SLI Deluxe, with two A-Data DDR2 800 1GB each. OS is Windows server 2003 R2.

Using cpu-z the memory frequency is reported about at 400MHz, presumably a correct value.

Now, I tried the same motherboard with a different cpu, a 5000+, instead of the 4600+
Surpripsingly to me, cpu-z now shows a decreased value of the memory frequency, at about 372 instead of 400. This using the same bios setup and no overclock or tweaking of any kind.

What is worst is that, although the general pc performance is very good, my application, now with the 5000+, worsened dramatically. I use that PC as home theater pc for viewing mpeg2/H.264 HDTV DVB-S2 broadcasts. While the 4600+ was able to display HDTV contents smoothly, now the 5000+, in spite of the fact that it should be positively better, behaves unaccetably jerky. Also CPU usage is 80%-90% in average, while the 4600+ was hardly more than 50% under any conditions.

Thank you for helping me solving this embarassing conundrum.
Marco
 

The_OGS

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Hi mazott,
The x2 4600+ uses a multiplier of 12x and this works fine to derive the 400MHz memory speed.
The x2 5000+ however uses a multiplier of 13x and because of the way AMD AM2 sets its memory speed you cannot get the perfect 400MHz.
Consider increasing the FSB until your memory hits the 400MHz speed - this would be an increase from 200 to ~215 or so.
Other than that, that's just how things work in AM2-land...
Make sure the AMD dual-core patch is installed and Cool&Quiet is not kicking in.
Funny how the 4600+ seemed to work better though... I would get into the BIOS with the 5000+ CPU and try to tune it up - if your performance seems to have decreased then the 5000+ may be weirding-out your memory settings.
Check CPU-Z for different latency timing settings between the two CPUs,
Regards
 

mazott

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Hi mazott,
Funny how the 4600+ seemed to work better though... I would get into the BIOS with the 5000+ CPU and try to tune it up - if your performance seems to have decreased then the 5000+ may be weirding-out your memory settings.
Check CPU-Z for different latency timing settings between the two CPUs,
Regards

Thank you for your hints. I successfully adjusted, as you suggested, the FSB to 215, actually getting the 400MHz.
However, the solution of my problem indeed came from another fix. I wrote earlier that I was running two comparable systems, both differing from each other for the cpu used, 4600+ the former and 5000+ the latter.
This was not reported accurately, since the 4600+ was running under XP, while the 5000+ was running under Server2003R2. Simply replacing Server2003R2 with XP sufficed to let the 5000+ work as due. Eventually, this would lend to to the conclusion that XP is substantially more efficient than Server2003, at least as to what concerns the world of DirectX.

Also, I installed a specific AMD driver for the dual core cpus, among other utilities found from AMD for similarly featured processors (http://www.amd.com/us-en/Processors/TechnicalResources/0,,30_182_871_13118,00.html ), with which I upgraded the driver originally shipped with XP. In your experience of dual core os handling, what do you think about its merit and necessity, possibly with specific regard of the strict requirements of my application?

Thank you and best regards, Marco
 

The_OGS

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Nobody is entirely sure exactly what the dual-core patch does - the best source of info is probably on AMD where you download it.
I understood it was a WinXP OS thing, helping Windows to use both cores.
Yeah, apparently HDTV really soaks up the clockcycles and you need lots of power.
The two low-wattage x2 3800+ CPUs would seem to be perfect little theatre-cube devices, but I think the x2 4600+ (65w) is actually the preferred CPU for this sort of thing, to get good performance.
Hey I've got an ATI HDTV Wonder - isn't the HDTV picture quality amazing? Even the mostly 1080i that I receive is really excellent.
L8R
 

mazott

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[...]
The two low-wattage x2 3800+ CPUs would seem to be perfect little theatre-cube devices, but I think the x2 4600+ (65w) is actually the preferred CPU for this sort of thing, to get good performance.

Yes, in fact I think that the x2 4600+ is the minimal ingredient in the HDTV recipe. Don't know that about Intel Core2 Duo chips though.

Hey I've got an ATI HDTV Wonder - isn't the HDTV picture quality amazing? Even the mostly 1080i that I receive is really excellent.
L8R

As the tuner card, I use a Technotrend DVB3200-S2 card, since my provider broadcasts in DVB-S2 only. The video card I settled with is a Nvidia 7600GT with Purevideo HDTV drivers.

With such setup, the x2 4600+ settles cpu utilization at a safe average of 50% and viewing is more than acceptable, both in H.264 and mpeg2 full hi-res.