Can you OC memory interface?

[computernewbie]

just wondering if u can OC mem interface on a GPU, i dont really understand how the radeon 4890 is faster than a gtx 285 even if the 285 has a higher mem interface...anyone feel like explaining

 

[jennyh]

The 4890 can be faster than a 285 because it has much higher *core* clock speed. In memory bandwith, the 285 will normally be 10% higher or so.

A 1ghz 4890 has a core at 1ghz, and a 285gtx has a core at ~675mhz or so. The 285gtx also has faster shaders, but less of them...although they are actually quite different by design so speed and numbers of shaders don't really matter per-se.

What matters is, both cards are pretty similar in performance - they just get to the same results in different ways. You can't compare cards from ATI and Nvidia on single aspects like core clock, shader clock or memory speed, it's how the whole package combines that matters.

 

[jennyh]

Here's a simple way to look at it.

Let's say there are 4 variables that determine overall speed of a graphics card.

1) Core speed
2) Shader speed
3) Memory speed.
4) Bus width.

I'm just going to use rounded figures and this is by no means scientific But you should get the idea from it.

ATI has 2x faster memory speed than Nvidia, but Nvidia has a bus width that can shift 2x more information at the same time. The end result is they are almost equal in memory bandwith.

Nvidia has 5x better shaders than ATI (note this isn't just about shader speed but takes in other aspects), but ATI has 3x more shaders. Nvidia has much better speed overall on sheer speed per shader.

ATI has 2x faster core speed, and this would make it easily be faster overall than Nvidia overall - however Nvidia has 2x more transitors so once again they are about the same.

At the end of that, you have two cards from two different makers and both are extremely similar in performance. In actual fact, Nvidia has more 'grunt' on their gpu's but the price is...price. It costs money for bigger buses, bigger chips etc - In terms of raw power Nvidia is ahead, but in terms of price/performance ATI is a long way ahead. That is why many consider ATI to be 'winning' the gpu battle right now.

 

[computernewbie]

ahh, i see...heh, i need to look at more benchmarks , i've seen some benchmarks on crysis and the 4890 does actually out perform the 285 in practically all setting, overclocked that is, although theres not much diff in a OC'd 4890 and the normal one. Gonna have to check the benchmarks of some of the games ill be playing, like supcom. If i may ask, what do you OC on a 4890? Is it the same as nVidia cards?

 

[jennyh]

Crysis is a bad game to be using as a benchmark tbh, especially for buying a graphics card.

Just use some common sense, and yes check out more benchmarks. There are actually very few graphics cards that are decent value for the money they are asking.

Imo the cards worth the money are -

4770
4850
gts250/9800gtx+
4870
gtx260 216 core
gtx275
4890

Truthfully, I think both the gtx275 and 4890 are overpriced but not as bad as say the gtx285 is.

OC'ing any graphics card is pretty much a simple case of downloading a software program and moving a couple of bars. For Nvidia's use evga precision and for ati's use rivatuner or catalyst control centre.

 

[computernewbie]

yes, ive been looking at the gtx 285 and it really is stagardly over priced, thats why i've been thinking of getting the gtx 260 216 core, i heard you coupld practically OC em to a gtx 285 and more. Either that, or get a vanilla gtx 285 (which is around..250?) and try to OC that to the factory OC'd gtx 285's they sell

 

[computernewbie]

oh yes, just another question i wanted to ask...mabad for double posting, are the graphics in ATI different in nvidia? When i say that, i mean like comparing the graphics of xbox 360 and PS3, both have different settings and such, one may look more "cartoonish", one may have better shading. Im not sure how these companys really produce the graphics card, so i dont know how differently these graphics cards really look and play

 

[jennyh]

No they are exactly the same in terms of the way the games look.

 

[computernewbie]

^- mkhay, thank you

Uh oh, been looking at some benchmarks, and its kind of weird how both nvidia and ATI work, it seems that when on lower settings, nvidia usually is ahead of ATI, but when the AA comes on, ATI skips ahead of nvidia, also the wattage is greather idle/load than nvidia. Mind i ask...Can i fit an extra fan to ATI cards? Seems as ATI cards run a bit hotter than nvid

Think i might go with ATI, as this is also my first build , i think ill go with SLI HD Radeon 4890, unless anyone else has any other recommendations?

Sorry if this is a bit off point too, but which brand manufacturer should i look for with ATI? I've been searching nvidia since i started, but now that i look at it, ATI seems to suit my needs more

Thanks