stevejlack
Technical User
Im having trouble posting, and im not sure whats wrong, im using pc2700 512 mb ram with a p4 2.6ghz 800fsb. My motherboard says it supports pc2700 but im not sure if i have to have ddr400 to run a p4 800fsb chip.
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is ddr400 a must for a p4 800fsb
- Thread starter stevejlack
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To get a better idea of what's going on, you have to first realize that the FSB and Memory bus are separate entities that don't necessarily need to operate at the same speed. The FSB can be running at 200MHz (quad-pumped to get 800MHz theoretical) and the memory bus could be 166MHz (doubled to get 333MHz theoretical). If the memory is in dual-channel, then you use a multiplier of 4 instead of 2. So for PC2700 in dual-channel, the theoretical speed would actually be 666MHz. You get the idea...
Although they don't have to match, it is often a good thing to try. The closer they are, the less latency there is. Latency is the time the chipset controller must wait to transfer data either from the CPU to memory or vice versa. If they're at the same speed, then technically you eliminate latency on the chipset and bus (although each RAM stick has its own built-in latency factor for processing local instructions).
In order to get the two to match, you would indeed need to buy two identical DDR400 sticks and place them in a dual-channel configuration.
~cdogg
[tab]"All paid jobs absorb and degrade the mind"
[tab][tab]- Aristotle
Although they don't have to match, it is often a good thing to try. The closer they are, the less latency there is. Latency is the time the chipset controller must wait to transfer data either from the CPU to memory or vice versa. If they're at the same speed, then technically you eliminate latency on the chipset and bus (although each RAM stick has its own built-in latency factor for processing local instructions).
In order to get the two to match, you would indeed need to buy two identical DDR400 sticks and place them in a dual-channel configuration.
~cdogg
[tab]"All paid jobs absorb and degrade the mind"
[tab][tab]- Aristotle
According to the documentation, you can run your memory off a 166MHz clock (DDR333 PC2700) while the cpu is running off a 200MHz clock (800fsb); according to the documentation... Many cases that will work, but sometimes it doesn't and there's no explaination other than "it doesn't work".
cdogg; dual-ddr configurations do not work at simultaniously transfering data, say PC2700 is still limited to the 2700MB/s limit even if it's in a dual-ddr configuration, dual DDR just allows the system to reach closer to the 2700MB/s limit.
cdogg; dual-ddr configurations do not work at simultaniously transfering data, say PC2700 is still limited to the 2700MB/s limit even if it's in a dual-ddr configuration, dual DDR just allows the system to reach closer to the 2700MB/s limit.
dakota,
My understanding of dual-channel DDR is that each chip, of course, is still limited to its max theoretical output. But you are effectively doubling the bandwidth by adding the two chips together.
For instance, DDR400 is normally only able to work at 400MHz, but in dual-channel configuration, two chips would effectively put out the same bandwidth as one chip running at 800MHz - although they are not necessarily running at that speed. The whole point is so the bandwidth and speed matches the P4's FSB.
That is why I said DDR333 in dual-channel would effectively operate at the "equivalent of" 666MHz.
~cdogg
[tab]"All paid jobs absorb and degrade the mind"
[tab][tab]- Aristotle
My understanding of dual-channel DDR is that each chip, of course, is still limited to its max theoretical output. But you are effectively doubling the bandwidth by adding the two chips together.
For instance, DDR400 is normally only able to work at 400MHz, but in dual-channel configuration, two chips would effectively put out the same bandwidth as one chip running at 800MHz - although they are not necessarily running at that speed. The whole point is so the bandwidth and speed matches the P4's FSB.
That is why I said DDR333 in dual-channel would effectively operate at the "equivalent of" 666MHz.
~cdogg
[tab]"All paid jobs absorb and degrade the mind"
[tab][tab]- Aristotle
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stevejlack
Technical User
I guess we will see what happens when it gets here, my mother board only has 3 dimm slots and does not have dual-channel capabilities. if the ddr400 does not fix the problem, i have no idea whats wrong, shouldnt it beep anyway, even if something is wrong
cdogg; but you still have a bottleneck between the chipset and the cpu (or wherever else the data is going) that is not expanded when in a dual DDR configuration. So with DDR333, you are still bottlenecked at 2700MB/sec even if you are using the dual DDR configuration. All dual DDR does is get you a little bit closer to achieving that 2700MB/sec limit.
stupid question:
does your motherboard support pentium 4 c's? (800 fsb)
what board do you have? it may not recognize the cpu if it is an older chipset. you say it only has 3 slots, which leads me to believe it is an 845 (or earlier?) chipset. the 865's and 875's generally have 4 slots, 2 blue 2 black for dual channel ddr.
for a p4c I would strongly recommend *at least* pc3200 (ddr400). You want the memory to run "1:1" meaning the cpu will handle the request from memory as fast as it possibly can. You can also run "5:4" which means for every 5 openings the cpu has to handle a request, the ram can hand it 4, meaning you are wasting that other request slot.
this would be a setup such as a moderately overclocked p4c 3.0 (1000 fsb instead of 800) with pc 3200 (800 fsb) 1000/800 = 5/4 = 5:4
we need to know what board you have
does your motherboard support pentium 4 c's? (800 fsb)
what board do you have? it may not recognize the cpu if it is an older chipset. you say it only has 3 slots, which leads me to believe it is an 845 (or earlier?) chipset. the 865's and 875's generally have 4 slots, 2 blue 2 black for dual channel ddr.
for a p4c I would strongly recommend *at least* pc3200 (ddr400). You want the memory to run "1:1" meaning the cpu will handle the request from memory as fast as it possibly can. You can also run "5:4" which means for every 5 openings the cpu has to handle a request, the ram can hand it 4, meaning you are wasting that other request slot.
this would be a setup such as a moderately overclocked p4c 3.0 (1000 fsb instead of 800) with pc 3200 (800 fsb) 1000/800 = 5/4 = 5:4
we need to know what board you have
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- #8
stevejlack
Technical User
I have a gigabyte GA-8s648FX(-L) mobo which does support 800fsb cpu up to 3.0Ghz, I am using a 2.6Ghz P4, with ram from crucial and a video card from powercolor, its a AGP8x 128mb radeon 9200. I wonder if the voltage on the video card is compatable with the mobo, I contacted the the video card company and they said it was but they could be wrong.
dakota,
Sorry, but I'm still not buying it. Take a look at this article:
This is just one of many sources that report 5.3GB/s bandwidth from DDR333 running in dual-channel. That's double the 2700MB/s you're talking about, because they are running at 128-bit instead of 64-bit when they are by themselves.
~cdogg
[tab]"All paid jobs absorb and degrade the mind"
[tab][tab]- Aristotle
Sorry, but I'm still not buying it. Take a look at this article:
This is just one of many sources that report 5.3GB/s bandwidth from DDR333 running in dual-channel. That's double the 2700MB/s you're talking about, because they are running at 128-bit instead of 64-bit when they are by themselves.
~cdogg
[tab]"All paid jobs absorb and degrade the mind"
[tab][tab]- Aristotle
Stevejlack
The issue you are talking about (video card voltage) applies to much older cards than the Radeon 9200.
There shouldn't be any problems using this card on your motherboard.
Martin
Replying helps further our knowledge, without comment leaves us wondering.
The issue you are talking about (video card voltage) applies to much older cards than the Radeon 9200.
There shouldn't be any problems using this card on your motherboard.
Martin
Replying helps further our knowledge, without comment leaves us wondering.
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stevejlack
Technical User
Well I got everything working, thanks for all your help, Consider this thread done with
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