What exactly is the difference...

[BlueMagician]

...between a 6800GT PCIe card and a 6800ULTRA PCIe card?

Is it just BIOS, and hence, differing stock clock speeds for GPU/RAM, or are there physical differences between a given manufacturers variants - ie: heatsink/cooler sizes, etc?

I have 2 x XFX 6800GT's, and of course am considering an overclock, but is the situation the same as with CPU production - do some GPU's/RAM come off the line as inferior samples and get clocked down etc etc, or is it likely that with good enough cooling I'll get Ultra clocks out of them?

Sorry for sounding like a newb, but, it's because I am... ...with overclocking... lol.


S.

[Olly1234]

Basically most GT's have 2.0ns Memory which runs at 1000mhz, and the Ultra's have 1.6ns memory that runs at 1200mhz, the 1.6ns memory and the cores on the Ultras are clocked higher, same pipes etc. However from what I read the Gainward 6800GT has its warranty all the way to 400/1100 with people running stable at 435/1200 so that makes it faster than a stock ultra for quite a bit less.

[Kezzer]

Basically the most GT's have 2.0ns Memory which runs at 1000mhz, and the Ultra's have 1.6ns memory that runs at 1200mhz, the 1.6ns memory and the cores on the Ultras are clocked higher, same pipes etc. However from what I read the Gainward 6800GT has its warranty all the way to 400/1100 with people running stable at 435/1200 so that makes it faster than a stock ultra for quite a bit less.

You call that basic? Here's basic;

The Ultra is faster.

[Olly1234]

Also quite a bit more expensive..

[BlueMagician]

...You call that basic? Here's basic;

The Ultra is faster...

Lol! Don't get me wrong, I just wanted to know what the exact differences in production/arcitechture were beween the two, so I could knew what chance I stood of ragging the nuts off my pair, as it were..

So, my GT's memory, being of the slower type could be a bottleneck, but the GPU's are the same... Hmmm ...

Thanks so far,
S.

[Olly1234]

Well the memory is rated at 1000 but in all likelyhood you'll see 1200 pretty easy

[StormPC]

Well the memory is rated at 1000 but in all likelyhood you'll see 1200 pretty easy

Yep, ratings don't mean much. My Corsair PC3200 is rated at 400 MHz (200x2) but runs 500 MHz with only 2.8V pretty easily. Quality beats ratings every time.

[BlueMagician]

...Quality beats ratings every time...

Lol, yup, I worked that one out by running my OCZ pair of 200MHz Plats @ 306MHz 2.5-4-4-8, as I type this...

I just wanna be careful, that's all, a pair of GFX cards totalling ~£600 is a bit different to ragging £190 of CPU or RAM...

Is it just temperatures and artifacts to look out for, or is there anything else I should know?

Many thanks guys,
S.

[StormPC]

I wish my FX-55 was £190.

[Spud1]

just out of interest what the point in you overclocking? Having 2X6800GTs in SLI mode is already faster than a 6800U, can't see that you'll get any performance gain at all - at least in current games. More likely to be your main CPU and RAM thats the bottleneck there.

[BlueMagician]

just out of interest what the point in you overclocking? Having 2X6800GTs in SLI mode is already faster than a 6800U, can't see that you'll get any performance gain at all - at least in current games. More likely to be your main CPU and RAM thats the bottleneck there.

I see healthy gains in the benches by increasing the GFX card clocks. I gained ~600 points in 3Dmark05 by going from 350MHz core to 402MHz, so it's not entirely CPU limited.

I agree that the CPU will be letting the side down a little, and don't think I'm gonna break the 10k barrier with it, but it sure is fun trying..

S.