Strange memory clock speed issue

[dbal]

I am a happy owner of a Club3D 7600GT AGP card and I accidentally discovered that the memory clock speed is only 1100 Mhz, instead of 1400Mhz, which is nVidia's reference board stock speed that every other 7600GT card manufaturer followed ever since its introduction.

I accept the fact that this memory speed is clearly stated in Club3D's website's page, so honesty is out of the question, but I just can't understand why they decided to supply the AGP (PCI-e runs on 1400Mhz) version of this card with rated 1400Mhz GDDR3 Samsung memory chips (I checked it by the codes on every single one) which in practice work only under 1100Mhz speed.

Any answer would be greatly appreciated....

 

[JustaGeek]

I believe it is due to the limitations of the AGP bus.

I have the 7800GS video card with only 16 pixel pipelines - 7800 GPU is built on the native PCIe and with 24 pipelines, so they decided to limit performance on the AGP version due to the AGP bus limitations.

 

[apoppin]

Originally posted by: JustaGeek
I believe it is due to the limitations of the AGP bus.

I have the 7800GS video card with only 16 pixel pipelines - 7800 GPU is built on the native PCIe and with 24 pipelines, so they decided to limit performance on the AGP version due to the AGP bus limitations.

it is an artificial limitation imposed by nvidia ... x1950p is AGP and not limited this way compared to the PCIe version

an 8xAGP is approximately equal to 4xPCIe ... plenty for 7600GT or 7800GS

 

[dbal]

Hmmm.....I don't know, I always thought that AGP limitations had to do with power supply to the card, that's why some are equipped with an additional PSU plug on the PCB. My card doesn't have that either but how is power supply needs related to memory speed? Besides, how did Leadtek manage to build a 7600Gt card with all speeds a proper stock settings?
Don't forget that I have Samsung GDDR3 chips on that are rated for 1.4Ghz...So, could this be an issue of using on the AGP variant, chips that didn't pass the validation process for the speed they were supposed to run??

 

[apoppin]

Originally posted by: dbal
Hmmm.....I don't know, I always thought that AGP limitations had to do with power supply to the card, that's why some are equipped with an additional PSU plug on the PCB. My card doesn't have that either but how is power supply needs related to memory speed?
Don't forget that I have Samsung GDDR3 chips on that are rated for 1.4Ghz...So, could this be an issue of using on the AGP variant, chips that didn't pass the validation process for the speed they were supposed to run??

Power to the card is just one difference. x1950p uses one or two power leads to supply power to the card the AGP slot cannot. AND the PCIe slot is ALSO limited to 75w ... that is WHY my 2900xt has 2 PCIe power leads feeding it besides the 75w PCIe

AGP is bandwidth limited compaed to PCIe. This is really not important - in gaming - until you get into the class of card like 8800GTS-640M or HD2900xt which would be somewhat limited by the AGP slot.
--Ask Stumps ... he tested a HD2900xt in his ASrock's 4xPCIe slot... it IS somewhat limited compared to the 16XPCIe slot

BUT, it appears - to me at least - that nvidia wanted to DUMP the AGP market so customers would migrate more quickly to PCIe and SLI. otoh, ATi belatedly decided to "corner" the diminishing AGP market with their "rialto" bridge chip that allows a x1950xt or x1950p ... or any GPU - to also be made AGP by their partners without much penalty.

imo, i believe nvidia "cut down" the AGP version to encourage you to upgrade to PCIe ... of course, this really IS in your best interests

EDIT: since you have the same vRAM as the PCIe cards, why not OC it?

 

[dbal]

Originally posted by: apoppin

AGP is bandwidth limited compaed to PCIe. This is really not important - in gaming - until you get into the class of card like 8800GTS-640M or HD2900xt which would be somewhat limited by the AGP slot.

BUT, it appears - to me at least - that nvidia wanted to DUMP the AGP market so customers would migrate more quickly to PCIe and SLI. otoh, ATi belatedly decided to "corner" the diminishing AGP market with their "rialto" bridge chip that allows a x1950xt or x1950p ... or any GPU - to also be made AGP by their partners without much penalty.

imo, i believe nvidia "cut down" the AGP version to encourage you to upgrade to PCIe ... of course, this really IS in your best interests

EDIT: since you have the same vRAM as the PCIe cards, why not OC it?

So, you think that Club3D simply followed nVidia's AGP bandwidth limitations recommendation and slowed the card down. Thing is that every attempt to OC, fails even when raising the mem speed by 50Mhz...That's why I talked about 1,4Ghz memory chips that failed to validate...

In case you didn't notice my edit in the previous post, check Leadtek's equivalent and try to explain how they managed to run the memory @ PCI-e speed....(1.4Gig that is). Sort of a rebel company right?

 

[apoppin]

did you up the voltage when you tried to raise the memory clock?

i believe nvidia allows their Partners some "latitude" in clocking the final product

 

[dbal]

Searching deeper in the issue, I also learned that all AGP variants of PCI-e designed graphics chipsets like the G73, have to carry the HSI bridge chip which is a significant -in terms of cost- addition to the manufacturer.
Tricks to lower the budget then must get in the game, and one common practice is lower the memory clock speed either by using lower rated memory chips or as in Club3D's case, defective-not validated for their initial rating memory chips that of course, have no overclocking potential at all.
Leadtek on the other hand, chose to create a card that would deliver all PCI-e specs to the AGP model, without caring for the final price tag but for the hapiness of the enthusiast that wants to squeeze all power out of the G73 core...Even if I can consider myself as one of these people, there is always a matter of availability here in Europe....

 

[evolucion8]

I couldn't said that better appoppin, those are artificial imposed limits, the only card that can start to saturate slighly the AGP BUS is the GeForce 8800 series and Radeon HD 2900 series. The only difference is that since AGP provides only 45W of Power vs the 75W of the PCIe, AGP cards requires more than 1 Molex connector vs it's PCIe counterpart. Usually the only thing that makes the PCIe shine over AGP is video streaming over the videocard, cause AGP is fast for downstreaming but not upstreaming. AGP8x downstream is about 2.1GB/s but upstream which I'm not sure it's between 266MB/s and 533MB/s