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Can someone explain the ps4's ram and how it compares to pc's?

#1KillerzOverHerePosted 10/6/2013 6:29:35 AM
I've read that gddr5 ram has higher bandwidth, but slower clock rate then ddr3 ram. But, if it is faster, why hasan't it been incorporated into pc's?
#2Flaktrooper123Posted 10/6/2013 6:37:45 AM
I believe it already has. Very good chance it is in your graphics card.
#3reincarnator07Posted 10/6/2013 6:38:57 AM
First, we DO use GDDR5, just not as main system memory. Unless you're running on integrated graphics, there is very little gain in going with faster memory. IIRC, it's a little more expensive than DDR3. Basically, there's no point.

The PS4 (and X1) both have AMD APUs, which have the GPU integrated with the processor. If they used DDR3 (hi X1!) then they will very likely run into bandwidth limitations with the GPU.
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#4KillerzOverHere(Topic Creator)Posted 10/6/2013 6:39:45 AM
i meant as system ram, does that mean that ps4's gpu shares the system ram? what if pc had replaced it's system ram with gddr5 ram? would it benefit or not? is gddr5 or ddr3 better for system ram, and if gddrr5 is, why isn't it incorporated as the system ram?
#5TimePharaohPosted 10/6/2013 6:42:29 AM
KillerzOverHere topic
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#6KillerzOverHere(Topic Creator)Posted 10/6/2013 6:44:09 AM
KillerzOverHere posted...
i meant as system ram, does that mean that ps4's gpu shares the system ram? what if pc had replaced it's system ram with gddr5 ram? would it benefit or not? is gddr5 or ddr3 better for system ram, and if gddrr5 is, why isn't it incorporated as the system ram?


thanks reincarnotor, answer the bolded question too?
#7AsellusPosted 10/6/2013 6:45:18 AM(edited)
I'd heard higher latency was the main reason it was deemed unsuitable for system ram - for graphics cards it's not a real problem because you've got thousands of threads running in parallel and it hardly matters if one stalls for a bit.

Had a rather hard time trying to find any definite answer as to how much more it is though, the above might mostly just be a characteristic of the way gpu memory controllers are designed.
http://www.dualshockers.com/2013/07/13/mark-cerny-on-ps4-gddr5-latency-not-much-of-a-factor/

Probably the better answer is that system ram bandwidth isn't a significant factor for performance unless you're running integrated graphics.

i meant as system ram, does that mean that ps4's gpu shares the system ram?

Of course.
#8JudgmenlPosted 10/6/2013 6:46:47 AM
Why would PCs use GDDR5 for system RAM when DDR4 is going be commercially available with Skylake?
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#9Mr kittyPosted 10/6/2013 8:52:47 AM
Shared memory is slower. Where the PS4 is slower is mainly on the CPU side. It should be better than the cell.
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#10The_AntiGrimPosted 10/6/2013 10:06:35 AM
TimePharaoh posted...
KillerzOverHere topic

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