quad channel ram vs gddr5?

drbaltazar

Mythbuster needed!OK interrupt wise ,which is better ;quad channel ram or gddr5(latency,performance etc)was wondering since gddr5 can open 2 memory page at once!and normal ram only one.would quad channel mean up to 4 memory page could be open at once?

Grunty

The last CPU that used page mode RAM was the Pentium. Specifically EDO RAM

Quizzical

One major reason why nothing except for the PS4 has ever used GDDR5 as system memory is that it caps you at four memory chips per 64-bit memory channel.  Right now, that limits you to 2 GB per memory channel.  Not that long ago, it would have capped you at 1 GB per channel.  If a dual channel setup limits you to 4 GB of video memory on a mid-range card, that's not a big problem.  Being unable to expand past 4 GB of system memory would be a problem, though.

The real trade-off between different memory standards is performance versus power consumption.  GDDR5 goes heavily for high performance at the cost of high power consumption.  DDR3 and DDR4 are more balanced.  LPDDR2 and LPDDR3 go for low power consumption at the expense of performance.

GDDR5 is built very much for high bandwidth.  I'm not sure about latency, but on a GPU, basically everything is high latency by CPU standards.  So even DDR3 on a discrete video card will probably be high latency just because it's used by a GPU.

drbaltazar

Originally posted by Quizzical

One major reason why nothing except for the PS4 has ever used GDDR5 as system memory is that it caps you at four memory chips per 64-bit memory channel.  Right now, that limits you to 2 GB per memory channel.  Not that long ago, it would have capped you at 1 GB per channel.  If a dual channel setup limits you to 4 GB of video memory on a mid-range card, that's not a big problem.  Being unable to expand past 4 GB of system memory would be a problem, though.The real trade-off between different memory standards is performance versus power consumption.  GDDR5 goes heavily for high performance at the cost of high power consumption.  DDR3 and DDR4 are more balanced.  LPDDR2 and LPDDR3 go for low power consumption at the expense of performance.GDDR5 is built very much for high bandwidth.  I'm not sure about latency, but on a GPU, basically everything is high latency by CPU standards.  So even DDR3 on a discrete video card will probably be high latency just because it's used by a GPU.

 

awesome info:so since gddr5 can use 2memory page at once :would gddr5 be better interrupt wise then quad channel ram?

drbaltazar

@quizzical:4 memory chip per 64 bit was probably an issue back in i5 2500k or even ps4 was being cooked but if I was to build a 2015 PC for gaming the GPU memory. Would be enough .isn't samsung working on. 4 GB memory chip?PS:do you know if ps4 make use of gddr5 dual memory page ?or sony just leave this at 1 (MSI/x)