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HD 6xxx question

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Tweak-venetica-

Tweak-venetica-

Member
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Joined
Aug 29, 2010
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in the push believe it or not
i seen so many leaks but one thing i dont see any one ask it this the 1600 mhz memory speed ?? thats x4 remember that !!

radeon_6000_series_gpu-z.png

check mine and check yours ! damin man that a float of 6400 mhz !!

mine
Capture005.jpg


put it on stock as the 6xxx is , now

HD 6xxx = 1600 * 4 = 6400
hd 4870x2 915 *4 = 3660 ( less than half ! ):chair: its a monster i tel you !
 
Physx is owned by nVidia (as of 2008) so I do not think think AMD gpus will have it onboard anytime soon..
 
Doesn't matter anyway, less than a dozen games use hardware Physx and they are all short and/or suck.

I saw that "6-series" GPU-Z when it was posted on Fudzilla or whatever, and really, there's nothing so far saying it's real. It would be nice, but that memory clock is really making me suspicious.
 
kayson said:
No, its 4.8Gbps memory bandwidth. The clock is really 600MHz. It's double data rate so the effective clock is 1200MHz because it transfers data twice every clock. The fastest GDDR5 is only like 2.1GHz. There's nothing close to 5...
Click to expand...

Correct me if I am wrong, but I believe GDDR5 is quad pumped so the bandwidth is broken down for example my 5850 runs at 1125mhz, so my bandwidth would be capped at 4.5Ghz. So the 6xxxx series card having memory clocks at 1600mhz being quad pumped would have a 6.4Ghz cap. Which btw is still very impressive if there is headroom for a decent OC.

Like I said kayson, correct me if I'm wrong, but I could just be saying Potato while you say Po-TAh-to.
 
scotchguy said:
Correct me if I am wrong, but I believe GDDR5 is quad pumped so the bandwidth is broken down for example my 5850 runs at 1125mhz, so my bandwidth would be capped at 4.5Ghz. So the 6xxxx series card having memory clocks at 1600mhz being quad pumped would have a 6.4Ghz cap. Which btw is still very impressive if there is headroom for a decent OC.

Like I said kayson, correct me if I'm wrong, but I could just be saying Potato while you say Po-TAh-to.
Click to expand...

GDDR = graphics double data rate
http://en.wikipedia.org/wiki/GDDR5
http://en.wikipedia.org/wiki/DDR_SDRAM

It runs on the rising and falling edge of the clock so it operates twice as fast as the clock frequency.

The 4.5 is the memory bandwidth and its measured in Gbit/s. If you look at the GDDR5 article, it says that it has double the data lines. So I'm guessing you have 4 data lines = 4 bits transferred every time. That's what takes you from 1.125GHz to 4.5Gb/s. Memory running at almost 5GHz would be insanity.
 
kayson said:
GDDR = graphics double data rate
http://en.wikipedia.org/wiki/GDDR5
http://en.wikipedia.org/wiki/DDR_SDRAM

It runs on the rising and falling edge of the clock so it operates twice as fast as the clock frequency.

The 4.5 is the memory bandwidth and its measured in Gbit/s. If you look at the GDDR5 article, it says that it has double the data lines. So I'm guessing you have 4 data lines = 4 bits transferred every time. That's what takes you from 1.125GHz to 4.5Gb/s. Memory running at almost 5GHz would be insanity.
Click to expand...

A 5870 has memory that runs at 1250Mhz. That's the raw, matter of fact mhz speed, but because it is quad pumped the effective speed is 5Ghz.

Much like DDR2 PC2 6400 is mostly referred to as running at 800Mhz because it is dual pumped, however its actual clock speed is 400Mhz.

The same goes for DDR3 PC3 12800 memory. It's listed at 1600Mhz but again, that is its effective speed as it is dual pumped, its actual speed is 800Mhz.

It isn't wrong as such to refer to these speeds as it gives us a clear indication on the capability of the memory in question, but it can be misleading.
 
Neural Net said:
A 5870 has memory that runs at 1250Mhz. That's the raw, matter of fact mhz speed, but because it is quad pumped the effective speed is 5Ghz.

Much like DDR2 PC2 6400 is mostly referred to as running at 800Mhz because it is dual pumped, however its actual clock speed is 400Mhz.

The same goes for DDR3 PC3 12800 memory. It's listed at 1600Mhz but again, that is its effective speed as it is dual pumped, its actual speed is 800Mhz.

It isn't wrong as such to refer to these speeds as it gives us a clear indication on the capability of the memory in question, but it can be misleading.
Click to expand...

Do you have any sources for that info? (specifically about graphics memory) Take a look at the newegg page for 5770's, for example:

http://www.newegg.com/Product/Produ...0&Order=BESTMATCH&Description=hd+5770&x=0&y=0

It lists the *effective* clock as 1200MHz. This would mean the actual speed is 600MHz since GDDR by definition is double pumped, not quad. If you notice, the memory bandwidth is always 4X the effective clock. Memory bandwidth is measured in bits per second and is not the same as a frequency. All this means is that the memory transmits 4 bits every effective cycle. The memory is still not operating at 4.8GHz... Bandwidth =/= frequency
 
kayson said:
Do you have any sources for that info? (specifically about graphics memory) Take a look at the newegg page for 5770's, for example:

http://www.newegg.com/Product/Produ...0&Order=BESTMATCH&Description=hd+5770&x=0&y=0

It lists the *effective* clock as 1200MHz. This would mean the actual speed is 600MHz since GDDR by definition is double pumped, not quad. If you notice, the memory bandwidth is always 4X the effective clock. Memory bandwidth is measured in bits per second and is not the same as a frequency. All this means is that the memory transmits 4 bits every effective cycle. The memory is still not operating at 4.8GHz... Bandwidth =/= frequency
Click to expand...

That listing on Newegg is wrong. Many are confused over the differences between GDDR5 and other DDR memory.

DDR/DDR2/DDR3 = two operations per clock cycle.

GDDR5 = four operations per clock cycle. Its arguable that it should be called QDR, but technically it's not QDR so it can't be called that officially.

It also clocks higher than GDDR3. The clock speed may seem high but to put it into perspective many old 8800 cards had GDDR3 running at over 1900Mhz effective and 800Mhz actual. You can buy system RAM that runs at 2000Mhz effective (1000Mhz actual).

If the effective clock speed on that 5770 was 1200Mhz (it's not, it's actual clock speed is 1200Mhz, and you times that by 4 for its effective speed = 4800Mhz) then the actual clock speed would be 300Mhz - but it's not, it's actually 1200Mhz. The reason this RAM has half the bandwidth of the RAM on the 5870 is due to it using a 128bit bus width as opposed to the 5870's 256bit bus width.

The bandwidth of individual chips is not an adequate indication of overall RAM performance because it depends on the number of chips used - i.e. the overall bus width. 4.8Gbps is the bandwidth of a single RAM chip and many are used to form the memory needed for a GPU.

Effective clock speed was never intended to be read as actual clock speed. The whole idea is to provide an indication of the bandwidth available and the best way to illustrate this is the total bandwidth figure, but the second best is to list the effective speed of the RAM. Average consumers understand Mhz whilst bandwidth in GB/s is a completely alien concept to them. This stems from CPUs originally being rated solely on their speed in Mhz more than anything else.
 
Neural Net said:
That listing on Newegg is wrong. Many are confused over the differences between GDDR5 and other DDR memory.

DDR/DDR2/DDR3 = two operations per clock cycle.

GDDR5 = four operations per clock cycle. Its arguable that it should be called QDR, but technically it's not QDR so it can't be called that officially.

It also clocks higher than GDDR3. The clock speed may seem high but to put it into perspective many old 8800 cards had GDDR3 running at over 1900Mhz effective and 800Mhz actual. You can buy system RAM that runs at 2000Mhz effective (1000Mhz actual).

If the effective clock speed on that 5770 was 1200Mhz (it's not, it's actual clock speed is 1200Mhz, and you times that by 4 for its effective speed = 4800Mhz) then the actual clock speed would be 300Mhz - but it's not, it's actually 1200Mhz. The reason this RAM has half the bandwidth of the RAM on the 5870 is due to it using a 128bit bus width as opposed to the 5870's 256bit bus width.

The bandwidth of individual chips is not an adequate indication of overall RAM performance because it depends on the number of chips used - i.e. the overall bus width. 4.8Gbps is the bandwidth of a single RAM chip and many are used to form the memory needed for a GPU.

Effective clock speed was never intended to be read as actual clock speed. The whole idea is to provide an indication of the bandwidth available and the best way to illustrate this is the total bandwidth figure, but the second best is to list the effective speed of the RAM. Average consumers understand Mhz whilst bandwidth in GB/s is a completely alien concept to them. This stems from CPUs originally being rated solely on their speed in Mhz more than anything else.
Click to expand...

So I read through the JEDEC GDDR5 Standard document, and it turns out you're half right. GDDR5 has two clocks: CK and WCK. The "effective clock" that's listed on websites like Newegg is the CK frequency.

Commands are registered on the rising edge of the CK clock. This means that it executes commands once per cycle. Addresses are registered on rising and falling edges of the CK clock. This is "double pumped".

Data (be it read or write) is clocked on the rising and falling edges of WCK. WCK is double the speed of CK.

There is no quad pumping in GDDR5. There are just two separate clocks both can be double pumped. The memory bandwidth comes from the fact that you get 2 bits of data transferred every WCK clock.

So if a GPU is listed as 1200MHz effective memory clock on Newegg, it means the following:

CK Clock: 1200MHz
Effective command clock: 1200MHz
Effective addressing clock: 2400MHz
WCK Clock: 2400MHz
Effective data clock: 4800MHz
"Memory bandwidth": 4.8Gbps.

I put that in quotes because its far from the true bandwidth. The memory can't constantly read in a stream of data. It's mostly limited by the latencies which are on the order of 8 CK clocks.

So yes, the data is read in at 4800MHz, but the operating clock of the memory is still 1200MHz.

Sources:
http://www.jedec.org/sites/default/files/docs/JESD212.pdf
http://www.hynix.com/datasheet/eng/...1=01&menu2=04&menu3=05&menuNo=1&m=3&s=5&RK=26
 
I agree with Kayson, i spend a headache generating chunk of time trying to figure out how gddr5 worked day before yesterday. He's got it.
 
kayson said:
So I read through the JEDEC GDDR5 Standard document, and it turns out you're half right. GDDR5 has two clocks: CK and WCK. The "effective clock" that's listed on websites like Newegg is the CK frequency.

Commands are registered on the rising edge of the CK clock. This means that it executes commands once per cycle. Addresses are registered on rising and falling edges of the CK clock. This is "double pumped".

Data (be it read or write) is clocked on the rising and falling edges of WCK. WCK is double the speed of CK.

There is no quad pumping in GDDR5. There are just two separate clocks both can be double pumped. The memory bandwidth comes from the fact that you get 2 bits of data transferred every WCK clock.

So if a GPU is listed as 1200MHz effective memory clock on Newegg, it means the following:

CK Clock: 1200MHz
Effective command clock: 1200MHz
Effective addressing clock: 2400MHz
WCK Clock: 2400MHz
Effective data clock: 4800MHz
"Memory bandwidth": 4.8Gbps.

I put that in quotes because its far from the true bandwidth. The memory can't constantly read in a stream of data. It's mostly limited by the latencies which are on the order of 8 CK clocks.

So yes, the data is read in at 4800MHz, but the operating clock of the memory is still 1200MHz.

Sources:
http://www.jedec.org/sites/default/files/docs/JESD212.pdf
http://www.hynix.com/datasheet/eng/...1=01&menu2=04&menu3=05&menuNo=1&m=3&s=5&RK=26
Click to expand...

That's pretty much exactly what I described in Layman's terms, I never said it was Quad pumped. If you really wanted me to go into more detail then you should have said.

I don't really like wasting time when you just regurgitated what the papers say. Otherwise what's the point?
 
Neural Net said:
That's pretty much exactly what I described in Layman's terms, I never said it was Quad pumped. If you really wanted me to go into more detail then you should have said.

I don't really like wasting time when you just regurgitated what the papers say. Otherwise what's the point?
Click to expand...

LOL dont take it personally...
 
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