New Mobility Graphics: Why only 128 bit bus?

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HarkovAdm

Limp Gawd
Joined
Nov 18, 2006
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I fail to understand why AMD and Nvidia are (according to wikipedia) crippling their best mobile graphics "solutions" with nothing greater than a 128 bit bus. Wasn't the entire reason that the desktop 4870 was so nice because it combined gddr5 and a 256 bit bus?

I don't understand what the point of a gigabyte of gddr5 is on 128 bits :(

I always considered 256bits the bare minimum, am I wrong to think this?
 
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size, heat, cost, complexity, etc

it isn't practical and isn't required in a mobile solution, and it really only matters for the person designing the circuit

the 4870 was "nice" for a variety of reasons, there is no single linear deciding factor that explains all differences between microprocessors
 
DDR5 negates the reduced bus speed. If it were DDR3 you would see issues. It's already been proven the 128bit bus doesn't limit the cards they've used it on. A high end 5870 would be a different story.
 
Think of it like water going through a hose - the hose being the bits and the water being the memory,

With GDDR3 and 256 bits, the hose diameter is large but the water rate is slow.

With DDR5 and 128 bits, the hose diameter is small but the water rate is extremely fast.

They offset using 128bits and DDR5. You can say that the cards are "crippled" but in return you get like people have said, less heat, size and cost.
 
Well I am well aware that gddr5 makes up for half the bus width, but I guess it just seems to me like it would be sweet if they kept the 256bit bus and used gddr5. Seems to me they're way too concerned about battery life and heat but I guess that's what they think people will pay for. Evidently I'm the only person who is disappointed
 
HarkovAdm said:
Seems to me they're way too concerned about battery life and heat but I guess that's what they think people will pay for.
Click to expand...

That's because most people do care about that, and cost

If heat and battery life and cost isn't a care for you, I might suggest a high end gaming laptop with a more powerful GPU and 256-bit memory bus, they do exist, there is a market for everyone
 
Armoured said:
Think of it like water going through a hose - the hose being the bits and the water being the memory,

With GDDR3 and 256 bits, the hose diameter is large but the water rate is slow.

With DDR5 and 128 bits, the hose diameter is small but the water rate is extremely fast.

They offset using 128bits and DDR5. You can say that the cards are "crippled" but in return you get like people have said, less heat, size and cost.
Click to expand...

a written image explains more than anything else i read so far.
 
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