GT 640 Synergy half memory clock

[Luke100000]

My GPU only use 800 of his 1600 MHz memory clock. When I try to overclock it, the computer will crash.

http://www.zotac.com/products/graph...er/DESC/amount/10/section/specifications.html

Maybe this can be usefull, I haven't found the exactly names:
Windows XP 32bit
CPU: 3*3,2 GHz
GPU: GT 640 Synergy
RAM: 3,25 GB

Thanks!

 

[Steve-007UK]

Are you 100% sure is running at 800mhz?

Could it be the fact it's sitting in power saving mode like 99% of todays GPU's do when idle?

I would download GPUz and run the render test to see if the speed jumps upto 1600mhz

 

[zsolt_93]

Its 800MHz but DDR3 has twice the effective clock so 1600MHz. Everything is okay with your card.

 

[Blue-Knight]

Its 800MHz but DDR3 has twice the effective clock so 1600MHz. Everything is okay with your card.

This and I would not trust much what the ZOTAC website says...

Here's the info for my 9500GT: http://www.zotac.com/products/graph...er/DESC/amount/10/section/specifications.html

It says it has 650MHz core clock, 1800MHz (900MHz) for memory and 1625MHz for shader while my card has 550MHz core clock, 1000MHz (500MHz) memory clock and 1350MHz for shader clock.

But you think the model is wrong? That's the model that is PRINTED on box and on my card. And the info for the DDR2 isn't correct either: http://www.zotac.com/products/graph...er/DESC/amount/10/section/specifications.html

Mine is GDDR2, 512MB, 550-500(1000 effective)-1350.

Disappointment. I would fire all the people in charge of that website.

But the card is good.

 

[Luke100000]

Are you 100% sure is running at 800mhz?

Could it be the fact it's sitting in power saving mode like 99% of todays GPU's do when idle?

I would download GPUz and run the render test to see if the speed jumps upto 1600mhz

Yes I've run the render test. Same result.

 

[Blue-Knight]

Yes I've run the render test. Same result.

It is correct, it shouldn't be at 1600. My card is 1000MHz effective and GPU-Z always show 499.5MHz.

Nothing wrong at all.

 

[Aquinus]

My GPU only use 800 of his 1600 MHz memory clock. When I try to overclock it, the computer will crash.

You're seeing the actual clock rate. DDR stands for Double Data Rate, which means it uses both the rising and falling edge of each clock cycle to transmit data. As a result, a base clock speed of 800Mhz would have a DDR "rate" twice as big; 1600Mhz. So I think you're misunderstanding what you're looking at.

 

[Steve-007UK]

Yes I've run the render test. Same result.

Sorry i was half asleep when i posted i also have to agree with people who have replyed.

You card might show 800mhz but the effective speed = 1600mhz

My HD7970 has GDDR5 and it shows as 1375mhz but its effective clock speed = 5500mhz

It's odd how they do it and can be very confusing.

 

[Aquinus]

My HD7970 has GDDR5 and it shows as 1375mhz but its effective clock speed = 5500mhz

It's odd how they do it and can be very confusing.

It's not that confusing, it's different technologies. GDDR5 is quad-pumped, or QDR (quad data rate, wikipedia.)

While I don't condone solely using Wikipedia for your information, its summary for QDR fairly streight to the point:

Quad data rate (or quad pumping) is a communication signaling technique wherein data are transmitted at four points in the clock cycle: on the rising and falling edges, and at two intermediate points between them. The intermediate points are defined by a 2nd clock that is 90° out of phase from the first. The effect is to deliver four bits of data per signal line per clock cycle.[1]

In a quad data rate system, the data lines operate at twice the frequency of the clock signal. This is in contrast to double data rate systems where the clock and data lines operate at the same frequency.[1]

QDR technology was introduced by Intel in their Willamette core Pentium 4 CPU, and is currently employed in their Atom, Pentium 4, Celeron, Pentium D, and Core 2 Processor ranges. This technology has allowed Intel to produce chipsets and microprocessors that can communicate with each other at data rates expected of the traditional FSB technology running from 400 MT/s to 1600 MT/s, while maintaining a lower and thus more stable actual clock frequency of 100 MHz to 400 MHz.[2]

 

[Luke100000]

Thanks! I think I understood this now.

 

[Aquinus]

Thanks! I think I understood this now.

I should really clarify this as terms tend to get thrown around but not properly used and I'm guilty of this.

The proper way of saying this is that you have DDR3 memory running at 800Mhz (1600MT/s) where MT/s stands for Mega (si-prefix) Transfers per second, since you're making two transfers for one clock cycle.

Once again, to quote wikipedia (which I should stop doing):

The units usually refer to the "effective" number of transfers, or transfers perceived from "outside" of a system or component, as opposed to the internal speed or rate of the clock of the system.

So it's important to make a distinction from clock rate and transfer rate.