SOLVED :) - why does 7800 GTXs RAM seem to clock higher than GTs?

[AthlonAlien]

1.6ns RAM = 1200-1250MHz effective

It seems to me that most 7800GTs (with decent cooling) can reach 1200-1250MHz on the RAM... that sounds on par... however, it seems that most 7800GTXs (with the same decent cooling) can reach upto 1350-1400MHz on the RAM?! Can anyone explain this? I thought they both used the same 1.6ns chips? Are the GTX just binned THAT well...?

-Thanks

 

[biostud]

GT are 1000 Mhz stock, GTX 1200MHz

 

[AthlonAlien]

I am refering to how far the Memory can be overclocked...

 

[Leper Messiah]

could definately be binning. I'm fine with mine running at 1215 though, its fast enough for me...

 

[Hacp]

Maybe the GTxs receive higher voltages?

 

[TheRyuu]

It has to be something with either voltages or binning.
RAM doesn't magically go up 200mhz out of nowere. Thats probably one of the reasons that the GT's cost less than the GTX's. RAM that is suitable for higher clocks cost more $$$.

Same go's with system memory. Higher clockable RAM cost more $$$. Like (i think) the CH-5/6's from inferion. They are sever class chips rated at DDR333 but perform with excelent timings at up to DDR550 at 2.7 volts with certain chips (thus binning).

 

[JBT]

I bet it has to do with latency too.
The 6800GT's had much tightier latency's than the 6800 Ultras. So often the ram couldn't clock to the same speeds but the GT's were sometimes pushing out the same FPS or more just with lower latency once the core clocks on the GT's was pushed up.

I wouldn't doubt the same holds true for the RAM on the 7800 GT's and GTX's.

Just remember highier clock speed always means better perfromance, right?

 

[rickon66]

I am pretty sure most all of the GT's have 2.0ns ram.

 

[AthlonAlien]

Originally posted by: rickon66
I am pretty sure most all of the GT's have 2.0ns ram.

After some more checking, it seems this is the case. My original source was incorrect Apparently most, if not all, GTs have the 2.0ns chips (even the eVGA 7800GT CO which comes factory clocked at 1100MHz, vs. 1000MHz for reference GTs)...

2.0ns chips are rated for 1000MHz
1.6ns chips are rated for 1200MHz-1250MHz

So I guess that explains it... a GT running at 1200 has been o/c about 200MHz, while a GTX running at 1400 has been o/c about 200MHz also.

 

[Mavrick007]

A good way to look at it is that the GTs are guaranteed at 1000mhz out of the box while the GTX is guaranteed at 1200 out of the box.

You might have good chips which could be the same rating, but the guarantee does not state that your GT would go as high as a GTX.. but it could with good cooling and a good batch of chips.

That's why sometimes you'll get a decent card in much the same way as a decent cpu where it will overclock much higher than it should (just because they had an alottment for a particular speed/type of product).

Usually any card will go higher than it's guaranteed to go.. so a GTX might go 100-200 higher than it is guaranteed to work and same as the GT, which could get your GT up to around the speeds of a GTX out of the box if you're lucky. That's why the GT is such a good deal right now.. but if you have to have the best, that's why you'll fork over the extra $ for the super fast 1.6 ns chips on the GTX.

If they're 1.6 on the regular GTX, just imagine how much better the chips are on the 512Meg GTX.. cause there's no way those chips are 1.6ns.. try around 1.2ns or even lower on those babies, and thus the huge price increase