Find if a graphics card has 64bit or 128bit memory bus \ VOGONS

Find if a graphics card has 64bit or 128bit memory bus

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First post, by okenido

Posted on 2018-03-30, 23:44

okenido Offline

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Is there a way to tell which bus width a GPU has, just by looking at the card ? This info is often not easy to find, I was wondering if we could calculate it from the ram chips datasheet.

For example I have two geforce 4mx440 cards, both have four memory chips on board :

- The first uses HY5DU561622CT-5 chips, labeled as " 256M(16Mx16) gDDR SDRAM" https://www.skhynix.com/eolproducts.view.do?p … =04&rc=graphics

- The second uses HY5DU283222Q chips, labeled as "128M(4Mx32) GDDR SDRAM" https://www.skhynix.com/product/filedata/file … oad.do?seq=4243

Does the "x16 / x32" in the chip description means their bus width is 16bit / 32bit ? So we could guess the first card has 4x16 = 64bit bus width, while the second has 4x32 = 128bit bus width ?

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Reply 1 of 4, by lazibayer

Posted on 2018-03-31, 02:35

lazibayer Offline

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The first one is 64bit. The second one could be either 64 or 128bit, because two chips can share the same data path.

Reply 2 of 4, by okenido

Posted on 2018-03-31, 10:33

okenido Offline

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You're right for path sharing, looking at the pcb it seems they are fairly independant

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I'll give it a try to see if the guessings are right 😀

Reply 3 of 4, by The Serpent Rider

Posted on 2018-04-01, 17:33

The Serpent Rider Offline

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That's reference GeForce 4 MX 440 board. They all were 128-bit.

I must be some kind of standard: the anonymous gangbanger of the 21st century.

Reply 4 of 4, by shiva2004

Posted on 2018-04-01, 22:57

shiva2004 Offline

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With late 90s/early 00s videocards most of the time it's simple: if you see a card with very obvious soldering points for additional memory chips it has a 64 bit memory bus, if not it's a 128bit, the reference design is the same and basically the wider bus uses more chips; later it become more complicated because 64bit and 128bit versions of a card started using different designs.

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This is a card with a 128 bit memory bus

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And this one has a 64 bit one

Sometimes there are memory chips on both sides of the card:

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128 bit

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64 bit

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