128 bit memory interface --> 7600gt

[chief5286]

A lot of the posts on here are concerned with the 7600gt's 128bit interface.
I know that more bandwidth is better, but can someone please point me to an article or explain exactly how this is something I should worry about for future games?

As it stands, a 7600gt can be had (after rebates) for $175. This is more expensive than a 6800gs, but only by $20 (again, after rebates). Yet the 7600 gives a significant increase in performance from the 6800gs. On a per-frame basis (using Anandtech's benches), the 7600gt is by far the better value, to the tune of $.50 for every fps. So, if the 7600gt is outperforming the 6800gs with its 256bit interface in todays games, why would/should I be hesitant to buy it based on its 128bit interface with respect to future games? How exactly would the interface limit performance?

I'd love to have a 7900gt, but again, it is 80% more expensive.
Thanks for any responses.

 

[Vokofpolisiekar]

I haven't looked at the benches, but 256bit is more future proof in certain cards. When you use AA+AF at high res, the 256bit interface handles the load much better. What they've done basically with the 7600, is use smaller die size (90nm) and this allows them to increase clock speeds along with GDDR memory also clocked higher. This willl allow it to beat a 6800, but it will break a sweat doing so.

Also, the 7600 and 6800 are two completely different architectures, so drawing comparison between them is a bit risky. I'd personally reccommend getting a 256bit interface that suits your needs if possible. The days of 1024x768 are over in the mid to high end sector, and at the least you should get a card that can handle 1280x1024 with AA and AF on.

I'm also talking in general, as I have no usefull knowledge of either of your mentioned cards.

 

[cleeve]

I personally wouldn't worry about the interface.

Bandwidth = clockspeeds x interface. So 128-bit memory @ 500 Mhz will perform the same as 256-bit memory @ 250 Mhz.

Now, the 7600 GT memory runs at 700 Mhz. With a 128-bit interface, that's 25 gb/sec.

The 6800 GS memory runs at 500 Mhz, with a 256-bit memory interface that's 35 gb/sec, so the 6800 GS has a 30% memory bandwidth advantage!

However, the 7600 GT's GPU runs at 560 Mhz, vs the 6800 GS's 450 Mhz... this is pretty much apples to apples - both GPUs are 12 pipelines, 5 vertex units and 8 Raster operation processors - so the 7600 has about a 20% increase in pixel pushing speeds.

So if the 6800 GS has a 30 % bandwidth advantage and only a 20% deficiency in pixels per clock, then how come the 7600 beats it every time? A couple reasons... probably #1 being that in newer, shader heavy games, it's the pixel processing that's bottlenecking the framerates, not the memory bandwidth.

But 7600 GTs are a much better bet at stock speeds though, with the next crop of games coming out of the woodwork and really stressing those pixel shaders. Plus, the 7600 GTs aren't any slouch when it comes to overclocking either.

Conclusion? If you're an overclocker, the 6800 GS might be the better card... 6800 GS owners who overclock their GPUs get phenomenal gains, and their results aren't hampered by their memory speeds. And for every Mhz you overclock the 6800 GS' memory, you're getting twice the milage out of it compared to overclocking a 7600 GT because of the memory interface.

The bottom line is, if you pick a 7600 GT over a 6800 GS, you're certainly not going to regret it later. If anything, the 7600 GT will wear better than the 6800 GS because of the higher core speed. The only reason to pick the 6800 GS is if you're a serious overclocker who wants to take advantage of that memory bus, and even then the 7600 GT is hard to dismiss.