Is the GTX 970 a 256bit card or not? I bought it because it was 256 bit.

[BirdDad]

I have read conflicting information about this, I would appreciate some clarification.
Thanks

 

[Despoiler]

The memory bus is 256bit wide yes. What do you think that means though because the phrasing of your question seems odd to me?

 

[stuff_me_good]

Damn, you could have bought card with 512 bit bus cheaper than that... congratulations.


Warning issued for trolling.

-Rvenger

 

[BirdDad]

memory bus width I specifically picked out a card that said it had a 256 bit memory width instead of a 128 bit.

 

[BirdDad]

Damn, you could have bought card with 512 bit bus cheaper than that... congratulations.

Are you speaking of an AMD card? No way I have used those since they were ATI- red screen of death over the smallest things.

 

[Despoiler]

memory bus width I specifically picked out a card that said it had a 256 bit memory width instead of a 128 bit.

Bus width isn't the only consideration. You need to know how fast the memory is clocked at to know the total memory bandwidth. Total memory bandwidth is the stat to compare between cards using the same memory technology. Either way if you have a 970 you did fine. Assuming you game at 1080p.

 

[Headfoot]

Are you speaking of an AMD card? No way I have used those since they were ATI- red screen of death over the smallest things.

That is in no way the case now. Your impressions are a decade out of date

 

[master_shake_]

That is in no way the case now. Your impressions are a decade out of date

this.

 

[Attic]

In short, yes it is 256bit. But not really. nVidia cleverly hid the "not really" part from folks who bought the card during and after release.

To touch on the concerns that gamers have, the GTX970 is 224bit wide (not 256bit) memory bandwith for up to 3.5gb's of the cards memory, not the full 4gb.

That's what got some folks peeved. nVidia was deceptive on how the specced and marketed the card initially. In addition to memory controversy, there was also inaccurate initial ROP specs and perhaps other.


From TechPowerUP

The way this partitioning works, is that the 3.5 GB partition can't be read while the 512 MB one is being read. Only to an app that's actively using the entire 4 GB of memory, there will be a drop in performance, because the two segments aren't being read at the same time. The GPU is either addressing the 3.5 GB segment, or the 512 MB one. Hence, there's a drop in performance to be expected, again, for apps that use up the entire 4 GB of memory.

While it's technically correct that the GTX 970 has a 256-bit wide memory interface, and given its 7.00 GHz (GDDR5-effective) memory clock, that translates to 224 GB/s of bandwidth on paper, not all of that memory is uniformly fast. You have 3.5 GB of it having normal access to the crossbar (the town-square of the GPU), and 512 MB of it having slower access. Therefore, the 3.5 GB segment really just has 196 GB/s of memory bandwidth (7.00 GHz x 7 ways to reach the crossbar x 32-bit width per chip), which can be said with certainty. Nor can we say how this segment affects the performance of the memory controller whose crossbar port it's using, if the card is using its full 4 GB. We can't tell how fast the 512 MB second segment really is. But it's impossible for the second segment to make up 28 GB/s (of the 224 GB/s), since NVIDIA itself claims this segment is running slower. Therefore NVIDIA's claims of GTX 970 memory bandwidth being 224 GB/s at reference clocks is inaccurate.

 

[bystander36]

Is there a specific reason you need/want 256-bits?

It's just a random stat on the card. While it may influence the performance, the actual performance is what you want to base your purchases from.

 

[BirdDad]

What's crossbar? Do you mean SLI?

 

[monstercameron]

Technically it is, it is like saying a r9 295x2 is a 1024-bit card.

 

[BirdDad]

Were not talking AMD what does it mean for Nvidia?
I am only running a single card will I get a performance hit above 3.5GB?

 

[cyclohexane]

Were not talking AMD what does it mean for Nvidia?
I am only running a single card will I get a performance hit above 3.5GBs?

Damn dude, can you at least write in coherent sentences? No one know what the hell you're talking about o.0

 

[BirdDad]

Is there a performance hit when the buffer is over 3.6GBs on a single card?

 

[master_shake_]

yes there is.

 

[BirdDad]

Thank you master_shake

 

[CriticalOne]

Technically yes, but is functionally a 224 bit card with only 3584 MiB of the 4 GiB readily accessible.

 

[SlowSpyder]

Technically yes, but is functionally a 224 bit card with only 3584 MiB of the 4 GiB readily accessible.

What he said, even if technically it is 256 bit. But how many 'bit' a card is doesn't really matter. What matters is how my vram you have and how much bandwidth you have. Bandwidth is determined by the width of the bus (128 bit, 256 bit, 384 bit, etc.) and the speed of the memory. Also GDDR5 transfers more data per clock than GDDR3/4.

For example, if you had two cards with DDR5, one with a 256 bit bus, the other with a 512 bit bus, if the card with the 256bit bus had memory that runs at 2x the clockspeed the bandwidth would be the same.

In the case of the GTX970 it has one of it's memory controllers disabled (I believe it has seven, the GTX980 has eight). It's still a good card, but Nvidia wasn't as up front as they should have been with how the card functions.

 

[BirdDad]

it is GDDR5

 

[RussianSensation]

Damn, you could have bought card with 512 bit bus cheaper than that... congratulations.

Don't tell him AMD is releasing 4096-bit HBM cards this month, 8X faster than his 970 for only 2X the price increase.


A forum member can't come in and ask a question about his/her card without you spewing this garbage? This is not acceptable behavior.

-Rvenger

 

[NTMBK]

What's crossbar? Do you mean SLI?

The "crossbar" is the internal bus on the GPU, which moves data between the shader clusters, the texture units, the ROPs, and so on.

 

[stuff_me_good]

Are you speaking of an AMD card? No way I have used those since they were ATI- red screen of death over the smallest things.

Classic case where average joe who knows nothing about nothing is so biased towards future buying decisions because of one bad experience 10 years ago and makes his life time shopping decision based on that. What is even worse that after that even years later when still knowing nothing about nothing keeps telling everyone outright lies based on his one bad experience in the past.

I wonder how those people get by in life when there is so many bad memories throughout life.


Not meant as personal insult, just pointing out of certain group of peoples mindset and buying habits. Yet it's really odd that when there has been numerous bad products from nvidia's side as well, I've never heard this kind of generalization towards their product, like in ever.

 

[HurleyBird]

Are you speaking of an AMD card? No way I have used those since they were ATI- red screen of death over the smallest things.

That was a long time ago. The way things stand for drivers right now:

Stability
AMD >>> Nvidia

Performance Optimization
Nvidia >>> AMD

 

[guskline]

Excellent explanation Attic.