Blackmagic Forum

Kind of a newbie hardware question here so please bear with me ...

Will my Intel i7 7820X CPU with its 28 PCIe lanes limit performance in Da Vinci Resolve, compared to an i9 7900X with its 44 PCIe lanes? Assuming that I will have two GPUs (GTX 1080 Ti), at least one M.2 drive and one SSD drive such as the Samsung EVO 850 and 950 on a Gigabyte X299 DESIGNARE EX motherboard.

Now I’ve read that 2 x GPUs aren’t recommended for Resolve as multiple GPU doesn’t necessarily mean a performance boost, but I also intend to use the machine for GPU 3D rendering hence the 2 x GPU.

More lanes are better if you are using more PCIe slots
please refer to the config guide for v15, link on the Bmd support web page

You always want more PCIe lanes imo. With only 28 lanes you will have to run one card at x8 instead of x16.

Honesty, this is why AMD is doing so well with Threadripper, even the cheapest one has 64 PCIe lanes.

Electric Black Sheep wrote:Now I’ve read that 2 x GPUs aren’t recommended for Resolve as multiple GPU doesn’t necessarily mean a performance boost, but I also intend to use the machine for GPU 3D rendering hence the 2 x GPU.

Where did you read that?

It's not true, multiple GPU's are absolutely recommended and most pro grading outfits have machines with multiple GPU's.

However, unlike Octane or Redshift, Resolve does prefer the same type of GPU since it scales down to the lowest memory GPU, so if you have a 1080ti and a 1060, the cumulative effect is more akin to 2 1060's. Also, (and this is also true for GPU renderers), a single 1080ti is better than two 1060's performance efficiency wise, but if you load up your machine with 4 1080ti's, Resolve will fly!

Dan Sherman wrote:You always want more PCIe lanes imo. With only 28 lanes you will have to run one card at x8 instead of x16.

Honesty, this is why AMD is doing so well with Threadripper, even the cheapest one has 64 PCIe lanes.

Yet Threadripper isn’t doing THAT well in benchmarks are they?

But so the x16 and x8 etc are the number of lanes they can run at, higher equals more throughput of data? So to run two cards at x16 I would need minimum 32 lanes from the CPU? Probably more since there are other components at play as well?

But am I correct in my assumption that storage uses PCIe lanes as well? Like from the M.2 slot? When editing video, fast storage and bus speeds must have a significant effect on performance ...

I am thinking that since performance vs. price isn’t linear. As in a twice as costly CPU doesn’t give you twice the performance, someone must have calculated the best build from a performance to cost ratio, no? A. k. a. Bang-for-the-buck, basically, that is what I am trying to do I guess ...

Electric Black Sheep wrote:

Dan Sherman wrote:You always want more PCIe lanes imo. With only 28 lanes you will have to run one card at x8 instead of x16.

Honesty, this is why AMD is doing so well with Threadripper, even the cheapest one has 64 PCIe lanes.

Yet Threadripper isn’t doing THAT well in benchmarks are they?

Not sure why you'd say this? My 1950X leaves the 7960X behind by a fair margin in Resolve.

Electric Black Sheep wrote:Yet Threadripper isn’t doing THAT well in benchmarks are they?

They are doing very well when you compare them dollar for dollar, and you aren't using gaming oriented benchmarks.

Electric Black Sheep wrote:But so the x16 and x8 etc are the number of lanes they can run at, higher equals more throughput of data?

That's correct.

Electric Black Sheep wrote:So to run two cards at x16 I would need minimum 32 lanes from the CPU? Probably more since there are other components at play as well?

That's correct as well.

Electric Black Sheep wrote:But am I correct in my assumption that storage uses PCIe lanes as well? Like from the M.2 slot? When editing video, fast storage and bus speeds must have a significant effect on performance ...

You need to check out the motherboard configuration and chip-set configuration to be sure.

Electric Black Sheep wrote: Bang-for-the-buck, basically, that is what I am trying to do I guess ...

For tasks that take advantage of multiple threads that is threadripper hands down right now.

Next year AMD will probably be better no matter what you are doing. they will be releasing ryzen2 and threadripper 2 on the zen 2 7nm architecture. Intel will be lucky if they can get their 10nm architecture out the door considering they delayed it yet again, and they have been doing it for years.