آنچه در مورد Dual Channel بايد بدانيد ...

[Gabana]

خوب...
چون خيلي از دوستان در اين مورد مشكل داشتن و سوال هم زياد مطرح ميشده تصميم گرفتم اينو ايجاد كنم تا بصورت علمي اين جريان رو بررسي كنيم
باز هم مثل همه تاپيك ها تاكيد مي كنم , پست بيهوده نديد !

[Gabana]

گفتم علمي پس چيزي از خودم نمي گم و گفته هاي سايت هاي سخت افزاري رو اينجا قرار مي دم

خوب..
داريم كه :

The system RAM memory prevents the PC of achieving its maximum capable performance. This happens because the processor (CPU) is faster than RAM memory and usually it has to wait for the RAM memory to deliver data. During this wait time the CPU is idle, doing nothing (that's not absolutely true, but it fits in our explanation). In a perfect computer, the RAM memory would be as fast as the CPU.

But it is very unprobable that RAM memory will one day reach CPU speed.

البته شايد روزي سرعت رم هم به سرعت پردازش پردازنده رسيد !

خوب در ادامه بايد بدانيم كه پردازنده داراي دو سرعت هست :

Many years ago one idea was created to match CPU speed with memory speed, which is used until today. The processor has two speeds, one internal – which is the one labeled on the CPU, like 3 GHz, 3.2 GHz and so on – and one external, used to access the CPU's outside world, specially RAM.

حالا دوال چنل چه مي كنه :

Dual Channel Memory can help improve the RAM speed, because this technique doubles it. In order to use Dual Channel Memory, your motherboard has to be capable of supporting this technique and you will also need two equal memory modules.

[Gabana]

قبلا در مورد فركانس پايه يا همون Real Clock در تاپيك OverClock صحبت كرديم . خلاصه ميشه گفت كه فركانس پايه توسط مادربورد توليد ميشه و قطعات ديگه از اين فركانس براي كاركردشون استفاده مي كنن - مثلا در پردازنده در Multiplier ضرب ميشه و Clock Speed داخلي پردازنده رو مي ده يا در AGP/PCI Bus تقسيم ميشه تا فركانس كاري فراهم بشه .
از طرفي گفتيم كه سرعت خارجي ارتباط پردازنده با ساير قطعات رو اينجا گفته External Bus Speed

AMD CPUs use a technique called DDR or Double Data Rate. With this technique the CPU transfers two data per clock cycle, doubling the performance of the bus since usually just one data is tranfered per clock tick. This technique is used since the very first Athlon processor and then with Duron, Sempron and Athlon 64 processors.

اينا براي قبل HT بوده و كاري هم با فرضيه HT فعلا نداريم :

[Gabana]

در اينتل هم مشابه چنين تعريفي رو داريم با اين تفاوت كه :

Intel CPUs use a technique called QDR or Quad Data Rate, which transfers four data per clock cycle. With this technique the CPU achieves an external performance four times greater than if it was transfering just one data chunk. Because of that, the clock advertised by Intel is four times greater than the real clock used by the CPU, as you can see on the table below.

[Gabana]

As we said before, once you know the maximum external transfer rate of your CPU it is just a matter of matching the memory transfer rate with it

حالا اينجا بحث در مورد Match كردن سرعت ترانفسر ( بين پردازنده و رم ) هستش ...



Transfar Rate ها رو ميبينيد ( اينا همه براي تك كانال بودن رم تعيين شدن )
يعني يك رم به تنهايي مي تونه چنين سرعت ترانسفري رو داشته باشه ( البته بر اساس اعداد و ارقام - تئوري )

Actually, if you have an AMD CPU you won't have problems. For instance, if you have an Athlon XP with 400 MHz (3,200 MB/s transfer rate) external bus just install DDR400 memories on your computer and it will work great since both the CPU and the memory will be running at the same speed grade (3,200 MB/s)

براي اينتل هم بهمين شكله - يعني FSB رو در نظر مي گيريد و رم متناسب رو انتخاب مي كنيد .

[Gabana]

Trasfer Rate رو در حالت دو كاناله ببينيم :

[Gabana]

براي مثال :

As for Pentium 4 CPUs with 800 MHz external bus, we need a 6,400 MB/s transfer rate and two DDR400 memory modules configured as Dual Channel are capable of giving that speed grade.

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نصب هم كه مشخصه :
بر اساس دفترچه مادربورد ميشه اسلات هاي مربوطه رو پيدا كرد .
دقت اينكه گاهي اسلات هاي هم رنگ مد نظره و گاهي غير هم رنگ ( كه اين يكي تقريبا ديگه نيست )
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يه مورد ديگه هم كه سوال بود اينه كه بجاي 1GB دو تا 512 بگيريم .؟

خب اينجا هم مهم External Bus Speed هست .
اما بصورت تئوري هميشه حضور دو تا رم Performance بهتري ارايه مي ده /

يه نكته هم در مورد پردازنده هاي سمپرون بگم :
Sempron Socket 754 از Dual Channel پشتيباني نمي كنه
[ برای مشاهده لینک ، با نام کاربری خود وارد شوید یا ثبت نام کنید ]

تست ها رو هم ببينيد :

I ran the Sandra memory bandwidth benchmark. This should show the greatest change between single and dual channel. This is a synthic benchmark, meaning this is what is available, but it is up to each application to take advantage of all the bandwidth. Below are the results from both the float point and integer.

[Gabana]

For the gaming benchmark I ran 3Dmark 2001 SE. It’s showing its age, but will show the greatest change in memory bandwidth. The current generation of video cards create a bottleneck in the CPU and memory performance.



My personal favorite for testing is SuperPi. It takes into account everything but the video card, unlike many of today’s benchmarks. It is a very simple program; it just calculates the desired number of digits of pi. I ran the one million decimal point test

[Gabana]

اينم از نتيجه ...

The boost in computer performance can be seen with dual channel memory. While the results aren’t breath taking, they do offer improvement for nothing. Running dual channel only means getting two memory modules instead of one, and setting them up correctly. If you want dual channel memory you can buy the dual channel pack or two of the individual modules. They will perform exactly the same. The price should be the same, or the two smaller modules may even be less.

Throwing twice as much RAM on the same amount of stick can cause a price increase. The only downside may be other factors relating to the memory, such as overclockability. You will only be able to run the memory at the speed or the worst stick. So if one of your modules can run 100 MHz faster then the other, it is stuck on the slower speed. If your computer supports dual channel, there is no reason why you should not be running it. Just remember that getting match pairs of memory, or even the dual kit, will save you a headache.

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سوالي بود بپرسيد
منابع :

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[seyyed.ali]

سلام دوست من
اگه توجه كنيد اينجا يه فرم فارسيه
در ضمن تشكر از مطلب فوق العادتون
لازم به ذكر مي دونم كه بگم اگر لطف كنيد و مطلبتون رو ترجمه كنيد بر ارزشش مي افزاييد
اگه what is dual channel رو توي google سرچ كنيم
توي همون لينك هاي اول به نتايج خوبي مي رسيم
مي بينيد كه جمع اوري مطلب زياد سخت نيست ولي ترجمس كه ارزشمندش مي كنه چرا كه قابل استفاده براي عموم و عوام ميشه

در هر حال ممنون و اميد وارم كه ناراحت نشده باشيد