ddr2 pc6400 800mhz ram frequency?

I just set up my biostar 550 mobo with 2 x 512 Corsair pc6400 c4 ram with 4-4-4-12 timings, and Athlon X2 3600+ dual core processor. Heres my question. With a 'Normal' bios setting with no overclock (yet) everything seems great.. Cpu and system temps are in the upper 20s and all is stable..

But running cpu-z I have the following question. On the Memory tab, under Timings, the 'Frequency' value is 382 mhz. And on the next tab, the SPD tab, under Timings Table, the Frequency is listed at 400 mhz.

Does that mean the system is not seeing my ram as the 800mhz ram that it is? Why or why not? Is there something that needs to be set differently in the bios? There IS a 'Memory Frequency' setting in the bios, but its only accessible via setting the 'Manual Overclock' options. It was originally set to 200 mhz.. I changed it to 800 mhz, but as soon as I either select 'Normal', or even ''automatic overclock', the Memory Frequency value Im talking about gets 'blued' out, with an 'X' in front of it meaning I presume, its ignored unless Im in Manual Overclock mode.

So, thats the question.. Should CPU-Z be reporting this mem frequency as 800 mhz? I dont suppose it could be something simple like, the 400 mhz its reporting is Per Channel, and since Im running dual channel, the real value would be interpreted as 400mhz x 2. Maybe the 400 mhz and 382 mhz frequencies Im seeing are fine.. I just need to make sure the system is not having a problem using the ram at its max speed.

thanks alot..


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More about ddr2 pc6400 800mhz frequency
  1. I didn't see anything to worry about. The physical speed of the RAM stick itself is 400Mhz, but as you said dual channel so 2x400Mhz=800 effective Mhz DDR2.
  2. Nova, thanks so much for the info. Re the multiplier, I just wanted to make sure I didnt waste money by buying the 800 mhz ram rather than the 667 or 533, or whatever the lesser frequencies are. I realize a small amt of it cant be used because of the multiplier issues fitting 'evenly', I still presume the 800 mhz ram was the better ram.. I also opted to pay a little extra for the Corsair c4 rather than the c5 ram, which gives me timings of 4s rather than 5s. Again, probably nothing Ill see or feel, but I got it anyway!

    Now all ive got to do is become comfortable with the cpu temperature rises when I let the biostar bios perform some simple overclocking. .Like this morning, I tried its V-6 setting.. This raised the bus speed from 201 mhz to 230 mhz, the cpu core speed from 1905 to 2185, and the cpu voltage from 1.3v to 1.552 v, as well as some other enhancements.. But it also raised the cpu temp from a stock norm of about 28 degrees to about 45-50 degrees. Thats with the HSF fan running at 1700 rpms.. When I increase it in response to the temp rise to about 2400 rpms, the cpu temp drops from about 45-50 degrees to about 35-38 degrees, which I Guess is ok, although Im still at the stage when I hate to do Anything which will raise the cpu temp.. I guess Ill get used to it after a while! ;)
  3. Quote:
    ... The physical speed of the RAM stick itself is 400Mhz, but as you said dual channel so 2x400Mhz=800 effective Mhz DDR2.

    Not exactly. For DDR2-800 (800MHz data rate), the underlying clock speed is 400MHz. Because of the "Double Data Rate" (DDR) design, two chunks of data are transferred per clock cycle, giving in this case an 800MHz data rate.
    Dual-channel mode doubles the throughput yet again, so DDR2-800 running in dual channel mode has a data rate of 1600MHz.
  4. Quote:
    ... I tried its V-6 setting.. This raised the bus speed from 201 mhz to 230 mhz, the cpu core speed from 1905 to 2185, and the cpu voltage from 1.3v to 1.552 v, as well as some other enhancements.. But it also raised the cpu temp from a stock norm of about 28 degrees to about 45-50 degrees. Thats with the HSF fan running at 1700 rpms.. When I increase it in response to the temp rise to about 2400 rpms, the cpu temp drops from about 45-50 degrees to about 35-38 degrees, which I Guess is ok, although Im still at the stage when I hate to do Anything which will raise the cpu temp.. I guess Ill get used to it after a while! ;)

    I certainly wouldn't use any MB's built-in general overclocking, as it's not likely to get it right. In your example above, the boost in the CPU voltage is enormous compared to the tiny percentage increase in core speed. I suspect your CPU could handle that speed increase with no/minimal voltage increase, so why stress the CPU unnecessarily and perhaps damage it?
  5. Quote:
    ... I tried its V-6 setting.. This raised the bus speed from 201 mhz to 230 mhz, the cpu core speed from 1905 to 2185, and the cpu voltage from 1.3v to 1.552 v, as well as some other enhancements.. But it also raised the cpu temp from a stock norm of about 28 degrees to about 45-50 degrees. Thats with the HSF fan running at 1700 rpms.. When I increase it in response to the temp rise to about 2400 rpms, the cpu temp drops from about 45-50 degrees to about 35-38 degrees, which I Guess is ok, although Im still at the stage when I hate to do Anything which will raise the cpu temp.. I guess Ill get used to it after a while! ;)

    I certainly wouldn't use any MB's built-in general overclocking, as it's not likely to get it right. In your example above, the boost in the CPU voltage is enormous compared to the tiny percentage increase in core speed. I suspect your CPU could handle that speed increase with no/minimal voltage increase, so why stress the CPU unnecessarily and perhaps damage it?

    Yea, real good point. I really have no abiding reason to overclock at this point, other than as an end in itself.. Fact is, I doubt I would detect any difference whatsover by raising the cpu speed from 1.9 to 2.1 ghz. So, other than as an exercise, Im not sure it makes alot of sense for me. As I learn more about it, Im sure I will try it again, but do it with the manual oc options and not the automatic ones they give you.

    Can you guys recommend a good benchmark utility I can use to compare my performance with others? Ive heard of prime95, but isnt that more of a system stressor than a benchmark? Id like to find something that would allow me to compare to the largest number of others..

    thanks..
  6. Quote:
    ... The physical speed of the RAM stick itself is 400Mhz, but as you said dual channel so 2x400Mhz=800 effective Mhz DDR2.

    Not exactly. For DDR2-800 (800MHz data rate), the underlying clock speed is 400MHz. Because of the "Double Data Rate" (DDR) design, two chunks of data are transferred per clock cycle, giving in this case an 800MHz data rate.
    Dual-channel mode doubles the throughput yet again, so DDR2-800 running in dual channel mode has a data rate of 1600MHz.

    Yea, but nobody ever sees a value of 1600 in the memory section of the cpu-z utility. .Instead, they see 400 when using pc6400 (800 mhz) ram running in dual channel mode.
  7. Quote:
    ... The physical speed of the RAM stick itself is 400Mhz, but as you said dual channel so 2x400Mhz=800 effective Mhz DDR2.

    Not exactly. For DDR2-800 (800MHz data rate), the underlying clock speed is 400MHz. Because of the "Double Data Rate" (DDR) design, two chunks of data are transferred per clock cycle, giving in this case an 800MHz data rate.
    Dual-channel mode doubles the throughput yet again, so DDR2-800 running in dual channel mode has a data rate of 1600MHz.

    My bad, thought dual channel was part of DDR2 :oops: 1600Mhz that's fast
  8. Quote:
    ... The physical speed of the RAM stick itself is 400Mhz, but as you said dual channel so 2x400Mhz=800 effective Mhz DDR2.

    Not exactly. For DDR2-800 (800MHz data rate), the underlying clock speed is 400MHz. Because of the "Double Data Rate" (DDR) design, two chunks of data are transferred per clock cycle, giving in this case an 800MHz data rate.
    Dual-channel mode doubles the throughput yet again, so DDR2-800 running in dual channel mode has a data rate of 1600MHz.

    My bad, thought dual channel was part of DDR2 :oops: 1600Mhz that's fast

    Yea, but like I said.. have YOU ever seen a ram speed of 1600 reported in CPU-Z? nope. IT always seems to report as it does in my system: 1/2 the value of the ram speed which you bought.. I have DDR2 PC6400 ram which as you know is 800 mhz ram running on a dual core cpu machine, so cpu-z reports the memory frequency at 382 mhz, and the spd tab reports the ram table frequency at 400 mhz...
  9. Quote:
    ...
    Yea, but like I said.. have YOU ever seen a ram speed of 1600 reported in CPU-Z? nope. IT always seems to report as it does in my system: 1/2 the value of the ram speed which you bought.. I have DDR2 PC6400 ram which as you know is 800 mhz ram running on a dual core cpu machine, so cpu-z reports the memory frequency at 382 mhz, and the spd tab reports the ram table frequency at 400 mhz...

    It's all a matter of using the correct tool. CPU-Z does NOT report memory throughput, it reports the *clock rate* of the memory bus. DDR2 RAM is rated by throughput, not by clock rate; for DDR2, the throughput is double the clock rate, so CPU-Z shows a 400MHz clock rate for RAM running at DDR2-800 throughput.
    Dual channel mode does not affect the clock rate, only the throughput. Thus, CPU-Z shows an unchanged clock rate, even though the throughput is doubled in dual-channel mode. If you want to measure the throughput, you've got to use something other than CPU-Z. You may want to try something like PC Wizard 2007.
  10. Thank you for recommending pc wizard. .I just installed the 2007 version, and its got some useful benchmark features... Im running the 3600+ x2 Brisbane amd cpu.. And it looks like its running pretty well in stock form, beating out even the 3800+ numbers in some cases, as well as the Intel D dual core pcs, as its supposed to. So, I guess things are running right, and I'll stop obsessing about cpu-z showing the spd ram value of my pc6400 dimms as 400, and the actual frequency as 382 mhz.. Guess its nothing to concern myself with.

    Now, once I read up some more, Ill start to try and overclock this some...
  11. Quote:
    ..., I guess things are running right, and I'll stop obsessing about cpu-z showing the spd ram value of my pc6400 dimms as 400, and the actual frequency as 382 mhz.. Guess its nothing to concern myself with.....

    Nope, it's because of the specific CPU model you are using. The AMD boards use a 200MHz base clock; this signal gets multiplied and divided to create the clocks used for the various system components. Your CPU has a 1900MHz core clock, created by applying a 9.5x multiplier to the base 200MHz clock. Since it is inside the CPU, the AMD x2 memory controller then divides the core 1900MHz signal to create a memory bus clock. Here's where the problem comes in: this divider has to be a whole number. We are trying to get to 400MHz (the clock speed for DDR2-800), but dividing 1900 by 4 gives us 475MHz, and dividing 1900 by 5 gives us 380MHz. Since all memory should work at slower-than-rated speed, but not all will work at higher-than-rated speed, the BIOS chooses 380MHz as the memory clock.
    To avoid this problem, you need a CPU with an even integer multiplier (e.g. 10x, 12x, etc).
  12. Quote:
    ..., I guess things are running right, and I'll stop obsessing about cpu-z showing the spd ram value of my pc6400 dimms as 400, and the actual frequency as 382 mhz.. Guess its nothing to concern myself with.....

    Nope, it's because of the specific CPU model you are using. The AMD boards use a 200MHz base clock; this signal gets multiplied and divided to create the clocks used for the various system components. Your CPU has a 1900MHz core clock, created by applying a 9.5x multiplier to the base 200MHz clock. Since it is inside the CPU, the AMD x2 memory controller then divides the core 1900MHz signal to create a memory bus clock. Here's where the problem comes in: this divider has to be a whole number. We are trying to get to 400MHz (the clock speed for DDR2-800), but dividing 1900 by 4 gives us 475MHz, and dividing 1900 by 5 gives us 380MHz. Since all memory should work at slower-than-rated speed, but not all will work at higher-than-rated speed, the BIOS chooses 380MHz as the memory clock.
    To avoid this problem, you need a CPU with an even integer multiplier (e.g. 10x, 12x, etc).

    Great response.. But, I thought it was a good thing that half digit multipliers were employed by certain cpus? Regardless, is my performance suffering in any kind of noticeable way by the implementation of this half multiplier, 9.5? What if it used 10.. then we'd have a cpu clock of 2000 mhz? Well, thats exactly what the 3800+ cpu has: 2.0 ghz, as opposed to my 2600+ cpu's 1.9 ghz. Now I got the 3600+ because its a 65nm brisbane unit, and because its been overclocked well to 3 ghz .. Its rep is to be a good overclocker; better than the Windsor amd dual cores. How I get there will take a ton more research on my part. But even if I dont, I cant imagine im suffering any noticeable slow down by the implentation you refer to. Nevertheless, the mathematical relationships between the related systems is fascinating... thanks again.
  13. You won't notice the difference between 380 and 400MHz.

    As you overclock it, you'll still be stuck with the 9.5x multiplier, so you'll be able to reach 400MHz when you get to a clock speed that is a whole multiple of 400. The nearest one is 2.0GHz, then 2.4 should work as well. 2.8 would also satisfy this. If you were to use 2.2 then you'd end up with 2200/5 = 440 or 2200/6 = 367.

    I think you can manually override these settings though. If, for example, you were at 2.5GHz you could override it to 416MHz instead of the slower 357.
  14. Quote:
    ... I tried its V-6 setting.. This raised the bus speed from 201 mhz to 230 mhz, the cpu core speed from 1905 to 2185, and the cpu voltage from 1.3v to 1.552 v, as well as some other enhancements.. But it also raised the cpu temp from a stock norm of about 28 degrees to about 45-50 degrees. Thats with the HSF fan running at 1700 rpms.. When I increase it in response to the temp rise to about 2400 rpms, the cpu temp drops from about 45-50 degrees to about 35-38 degrees, which I Guess is ok, although Im still at the stage when I hate to do Anything which will raise the cpu temp.. I guess Ill get used to it after a while! ;)

    I certainly wouldn't use any MB's built-in general overclocking, as it's not likely to get it right. In your example above, the boost in the CPU voltage is enormous compared to the tiny percentage increase in core speed. I suspect your CPU could handle that speed increase with no/minimal voltage increase, so why stress the CPU unnecessarily and perhaps damage it?

    Upon rereading this, I must be missing something. Im seeing the CPU Voltage increase (1.3 to 1.552) as a 19% increase, and Im seeing the cpu frequency increase (1900 to 2185) as a 15% increase.. Do you really consider the CPU Voltage increase of 19% to be 'Enormous' compared to the CPU frequency increase of 15% which you say is Tiny? Sure, theres a difference... around 4%... but I wouldnt exactly call it an 'Enormous' difference.. Im new to overclocking, so I am open to the possibility that its possible that in this realm, these kinds of percentage magnitudes are correctly described as you have. But I just wanted to make sure before I proceed to try and get some more cpu frequency out of my x2 3600+ cpu, which Ive read, is supposed to be an excellent overclocking candidate.

    BTW, can someone give me a definitive CPU Temperature value above which I need to make sure NOT to go? Im currently idling around 28-31 degrees after the pc has been running for a couple of hours. This temperature only requires a cpu HSF speed of about 1750 rpms, which is only about 60% of its max rpms. Im liking this speed alot, but Im pretty sure that as I start testing OC settings, that may climb by 10 to 15 degrees, and I need to be sure that this is still acceptable.

    Thanks much.
  15. Quote:
    ...Im seeing the CPU Voltage increase (1.3 to 1.552) as a 19% increase, and Im seeing the cpu frequency increase (1900 to 2185) as a 15% increase.. Do you really consider the CPU Voltage increase of 19% to be 'Enormous' compared to the CPU frequency increase of 15% which you say is Tiny?

    Yes, because each needs to be considered against its own possible range of values. CPUs are VERY sensitive to small voltage differences. One would expect many/most CPUs to be able to handle a 15% clock boost even without ANY voltage increase. Another example: to get my Pentium D 805 to run happily at 3.68GHz (stock speed 2.66GHz, so 38% speed boost), I increased the CPU voltage by 0.05V from the 1.35V base (a 3.7% voltage boost).
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