Personal computing discussed

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wildman666
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overclocking ram.

Thu Jun 07, 2007 1:50 pm

Why is ram overclocked only by 133 increasement?
Sorry if my english aint understandable.
 
king_kilr
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Thu Jun 07, 2007 1:58 pm

RAM can be overclocked in increments determined by your motherboard, for most it is possible to adjust in 1MHz increments.
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wildman666
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Thu Jun 07, 2007 2:14 pm

1.Whats the lowest latency amds ht can use/benefit?
2.Is there any speed and temp difference in cpus that have the same clock speed but different mult and fsb?
Last edited by wildman666 on Thu Jun 07, 2007 2:16 pm, edited 1 time in total.
 
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Thu Jun 07, 2007 2:15 pm

The standard RAM speed grades tend to be in 133MHz increments for historical reasons.

By definition, overclocking means running the RAM at a non-standard speed. The increments available for overclocking are determined entirely by the motherboard and the memory controller used on it.
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just brew it!
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Thu Jun 07, 2007 2:18 pm

wildman666 wrote:
1.Whats the lowest latency amds ht can use?

HT is not the memory bus. HT is used to communicate between the CPU and the chipset.

2.Is there any speed and temp difference in cpus that have the same clock speed but different mult and fsb?

If you are talking about CPU cores which are otherwise identical (i.e. same core stepping), higher FSB will generally give you better performance in apps which are constrained by external bandwidth, along with slightly higher temps.

If the CPU cores are different, then all bets are off.
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wildman666
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Thu Jun 07, 2007 2:40 pm

HT is not the memory bus. HT is used to communicate between the CPU and the chipset.

Then whats the lowest latency k8 or even k10 can tehnically use?
 
Klyith
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Thu Jun 07, 2007 2:47 pm

wildman666 wrote:
HT is not the memory bus. HT is used to communicate between the CPU and the chipset.

Then whats the lowest latency k8 or even k10 can tehnically use?

The lowest latency to memory depends on what ram you buy and what settings it can run at. Take a look at this old post I wrote on the subject. It's about DDR rather than DDR2 so the numbers are a bit different, but the calculations are the same.


For the HT bus, which is what the CPU uses to communicate to everything else in the system other than ram, latency would be determined solely by how fast your mobo/chipset lets you crank it up. But latency is not really an issue for HT.
 
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Thu Jun 07, 2007 3:20 pm

wildman666 wrote:
Then whats the lowest latency k8 or even k10 can tehnically use?

It depends on many, many factors --

- DDR or DDR2?
- What memory clock speed?
- Which motherboard?
- What brand and speed of DIMMs?
- Are DIMMs single- or double-sided?
- How many DIMMs installed per channel?
- Overvolting the memory controller and/or DIMMs?

There is no simple answer to the question "What's the lowest latency I can get with CPU X?"
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wildman666
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Thu Jun 07, 2007 3:21 pm

ok i read the article a bit so now i want to know what are
command rates t0,1.2.3 and their performance impact.
 
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Thu Jun 07, 2007 3:33 pm

Command rate is how long the memory controller needs to wait (in clock cycles) between selecting a given set of DRAM chips for access, and sending the first read or write command. Lower number for command rate gives you better performance.
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Usacomp2k3
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Thu Jun 07, 2007 3:34 pm

This might be good reading for you:
http://techreport.com/etc/2005q4/mem-la ... dex.x?pg=1
 
wildman666
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Thu Jun 07, 2007 3:50 pm

1.Whats the differnece between ddr vs gddr exept that gddr works on gpus?
 
Klyith
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Thu Jun 07, 2007 4:00 pm

Edit: The performance impact of 1T vs 2T is increased bandwidth. On plain DDR is could be up to 15% in synthetic tests (less on DDR2). But overall system impact is much less, even in high-bandwidth applications. It's in the "nice to have" area if your ram can use it.

wildman666 wrote:
1.Whats the differnece between ddr vs gddr exept that gddr works on gpus?

http://en.wikipedia.org/wiki/DDR-2#Rela ... DDR_memory
http://en.wikipedia.org/wiki/GDDR3
http://en.wikipedia.org/wiki/GDDR4
http://en.wikipedia.org/wiki/GDDR5

Short answer: almost nothing, but with some features added / removed / tweaked to work better on graphics cards.

I'm about this close to breaking out the JFGI link.
Last edited by Klyith on Thu Jun 07, 2007 4:07 pm, edited 1 time in total.
 
wildman666
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Thu Jun 07, 2007 4:04 pm

I guess this it ......for today.
 
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Thu Jun 07, 2007 4:33 pm

If you are having performance problems, please list your complete config and which programs/games you are having trouble with. May be we can help you better.
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