محاسبه پهنای باند حافظهMemory Bandwidth

[AORUS 8512]

سلام
روش محاسبه پهنای باند حافظه یا Memory Bandwidth

(bus/8)*(memory clock*2)

مثال:نتیجهGB/s
حافظه گرافیک 4 گیگ با باس 128 بیتی و کلاک667

21.344 =(667*2)*(128/8)

باس ضرب در 2 همون فرکانس Effective میشه.Pump Rateبهش میگن-DDRدابل هست.

از جناب Abrahamبابت راهنمایی سپاسگزارم-تاپیک از حالت سوال خارج شد.

ویرایش شده می 21, 2014 توسط helenjoon

[Abraham 714]

کلاک ضربدر ( بیت بر کلاک تقسیم بر 8 )

فکر کنم بشه:

667*(128/8)=10672 MB/s 10.672 GB/s

[AORUS 8512]

کلاک ضربدر ( بیت بر کلاک تقسیم بر 8 )

فکر کنم بشه:

667*(128/8)=10672 MB/s 10.672 GB/s

سلام

فکر کنم بیشتر بشه و روش درست نباشه-بابت راهنمایی ممنونم.

Rated Memory Frequency (1333Mhz) x 64 x 2 divided by 8 = Memory Bandwidth

یه مثال دیگه که پیدا کردم

 

The Titan has a 384bit bus while a GTX 680 only has 256, hence 50% more memory bandwidth (assuming clock and latencies are identical.

Edit: I'll try to explain the whole concept a bit more: the following is a simplified model of the factors that determine the performance of RAM (not only on a graphics cards).

Factor A: Frequency

RAM is running at a clock speed. RAM running at 1 GHz "ticks" 1,000,000,000 (a billion) times a second. With every tick, it can receive or send one bit on every lane. So a theoretical RAM module with only one memory lane running at 1GHz would deliver 1 Gigabit per second, since there are 8 bits to the bytes that means 125 Megabyte per second.

Factor B: "Pump Rate"

DDR-RAM (Double Data Rate) can deliver two bits per tick, and there even are "quad-pumped" buses that deliver four bits per tick, but I haven't heard of the latter being used on graphics cards.

Factor C: Bus width.

RAM doesn't just have one single lane to send data. Even the Intel 4004 had a 4 bit bus. The graphics cards you linked have 256 bus lanes and 384 bus lanes respectively.

All of the above factors are multiplied to calculate the theoretical maximum at which data can be sent or received:

**Maximum throughput in bytes per second= Frequency * Pumprate * BusWidth / 8 **

Now lets do the math for the two graphics cards you linked. They both seem to use the same type of RAM (GDDR5 with a pump rate of 2), both running at 3 GHz.

GTX-680: 3 Gbps * 2 * 256 / 8 = 192 GB/sGTX-Titan: 3 Gbps * 2 * 384 / 8 = 288 GB/s

ویرایش شده می 21, 2014 توسط helenjoon

[AORUS 8512]

فکر کنم اینطور محاسبه میشه:

memory in gigabyte  *C )* (bus/8) =bandwidth)

 

if gddr3 c=1

if ggdr5 c=2

ویرایش شده می 21, 2014 توسط helenjoon

[AORUS 8512]

روش صحیح بدین شکله

(bus/8)*(memory clock*2)

مثال:نتیجه  GB/s

گرافیک 4 گیگ با باس 128 بیتی و کلاک667

21.344 =(667*2)*(128/8)

باس ضرب در 2 همون فرکانس Effective میشه.