Why do card manufacturers underclock the memory?

[chssvl]

I just bought a radeon 9700 pro. Reading several reviews I saw that the card comes with 2.8ns Samsung RAM which translates into roughly 357Mhz (714DDR). However, the speed is set at 310Mhz. My question is, if the memory is capable of doing such speeds, why do manufacturers underclock them in their video cards?

i know that sometimes they do that in lower spec cards to make a difference in performance between this cards and their higher end cards. but when the 9700 pro came out it was the top of the line for ATI so why bother? Why didn't they just configured the memory at the rated speed and get better performance in the process?

 

[RichPLS]

The milage varies with oc'ing, and yeilds are not high enough to insure that at higher speeds stability problems will not raise its ugly head. Keep in mind, this is especially true for the product launch, then later production processes are refined.
And by then, they are promoting thier next card.





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[chssvl]

But if a memory manufacturer rates it at a certain speed, doesn't that mean that this manufacturer certifies that it will work at this speed during the expected life span? If Samsung says that their memory is meant to work at 357Mhz why does ATI say that it must run at 310Mhz?

 

[RichPLS]

They all dont use same memory.



========================
Try everything...
Do not be afraid of failure, for this is how we learn and grow...
Live life to the fullest...
Do not regret what you have not yet done!!!

 

[TheGreatGrapeApe]

ATI and nV set minimum standards for the boards, and then the board maker gets the parts they can to match that spec. Some can find cheap deals on 2.86ns Samsung memory (Hynix is the 2.8ns stuff) and thus put that in there, theres can only afford 3.0ns Samsung memory and they put that on there, both are still within spec, but one is a better overclocker.

So the minimum allows them flexibility within reason, but not too much.

BTW, the Samsung memory is <A HREF="http://216.239.51.100/search?q=cache:qcJDK0GIP3cC:www.samsungelectronics.com/semiconductors/Graphics_Memory/DDR_SDRAM/128M_bit/K4D26323RA/k4d26323ra-gc.htm+samsung+K4D26323RA&hl=en&ie=UTF-8" target="_new">rated for 350mhz</A> (as it's <A HREF="http://www.hardocp.com/image.html?image=MTA1MDI2NTI3OHViYWF1RTBZM3lfMV8xMF9sLmpwZw==" target="_new">2.86ns and should look like this</A>). The Hynix memory is rated for faster because it is the 2.8(0)ns memory, however in practice the Samsung memory usually overclocks far better than the Hynix memory despite the ratings.

Most of it is about flexibility. IF you look at Sapphire's cards you'd see a whole whack of memory on it. And if you look at Tyan's R9600Pro you'd see that the card has a stock speed of 300mhz but the memory is only rated for 275mhz! So really in the end it's up to the board makers. Now with GDDR3 there's less and less options for the time being, that may change, but for now there are few suppliers and limited options.


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