GPU Link Speed not good rx 580 and 5770

[VillasManzanill]

Hello
I have a

RX 580 8gb ROG STRIX Asus (pci e slot 1, its a huge card, takes 2.5 slots)

5770 1gb apple stock (pci e slot 3)

my system is
5,1
X5690 x 2
96gb ram 3 16gb ram slots in each processor

and here my link speed benchmarks of opencl ocean wave 1.61 attached

with only the rx 580 my speed is 3gb speed and
with the 2 gpus it drops down to 1.5gb

Why does it drop down to 50% with 2 gpus?

i have tried the configuration of

rx 580 slot 2
5770 slot 1

Same bad results.

if you know how to fix this it will be awesome
thanks!

 

[h9826790]

Hello
I have a

RX 580 8gb ROG STRIX Asus (pci e slot 1, its a huge card, takes 2.5 slots)

5770 1gb apple stock (pci e slot 3)

my system is
5,1
X5690 x 2
96gb ram 3 16gb ram slots in each processor

and here my link speed benchmarks of opencl ocean wave 1.61 attached

with only the rx 580 my speed is 3gb speed and
with the 2 gpus it drops down to 1.5gb

Why does it drop down to 50% with 2 gpus?

i have tried the configuration of

rx 580 slot 2
5770 slot 1

Same bad results.

if you know how to fix this it will be awesome
thanks!

What it says here?

 

[VillasManzanill]

im attaching pics

 

[h9826790]

im attaching pics

In this case, unless you really see a bug performance drop in real application, I wouldn't worry too much about it.

Oceanwave is pretty old now, and no one knows how accurate it can handle multi GPU config.

Anyway, in your case, you better install 5770 in slot 1, and RX580 in slot 2. So that both card can run at x16.

 

[VillasManzanill]

ok thanks
is there any other program that can do a similar test (pci speed link gpu) as oceanwave ?
with 1 gpu it says my speed its 3gb

 

[h9826790]

ok thanks
is there any other program that can do a similar test (pci speed link gpu) as oceanwave ?
with 1 gpu it says my speed its 3gb

Don'y know, but IMO the best way to test it is to run real benchmarking software.

e.g. Luxmark V3, or Unigine Valley.

Especially Luxmark, It can clearly shows each GPU's contribution. So that it allow you to easy compare if the GPU's performance drop significantly if the 2nd GPU installed.

Also, it can tell if you should install the 2nd GPU (if overall score drops after 2nd GPU installed).

 

[VillasManzanill]

i changed the location of the gpus slots now i have

rx 580 slot 2 system says its at 8x
5770 slot 1 system preferences says its at 16x

whats with that
here screen shots

 

[h9826790]

i changed the location of the gpus slots now i have

rx 580 slot 2 system says its at 8x
5770 slot 1 system preferences says its at 16x

whats with that
here screen shots

That means Oceanwave actually reporting the correct number. AFAIK, it always report the 2nd GPU's bandwidth.

So, in your case. If RX580 in slot 1, and 5770 in slot 3.

It detect PCIe 2.0 x4, and shows 1.5GB/s

If you put 5770 in slot 1, and RX580 in slot 2.

Then it detect PCIe 1.1 x8, coincidentally equals to PCIe 2.0 x4, therefore, also display 1.5GB/s.

But I really have no idea why the RX580 can only connect as a x8 when you put that in slot 2.

 

[irontony21]

The RX 580 that we use are not Apple "Blessed" as they do not contain Apple firmware. This is a known limitation when using generic Windows AMD/ Radeon Graphics cards in Apple Macs. Stop worrying about it and enjoy your new RX 580. (mine is the same max Link Speed is 2.5G)

 

[h9826790]

The RX 580 that we use are not Apple "Blessed" as they do not contain Apple firmware. This is a known limitation when using generic Windows AMD/ Radeon Graphics cards in Apple Macs. Stop worrying about it and enjoy your new RX 580. (mine is the same max Link Speed is 2.5G)

Problem is not 2.5G, but PCIe x8.

Is that a known issue for RX580?

 

[VillasManzanill]

after reboot now they both show as 16x lane
im using os x 10.13
how weird

 

[h9826790]

after reboot now they both show as 16x lane
im using os x 10.13
how weird

Then better not to touch it now.

Anyway, Oceanwave now should read the RX580's link width and speed, that means now you should see ~3GB/s.

 

[Appleham]

Hello
I have a

RX 580 8gb ROG STRIX Asus (pci e slot 1, its a huge card, takes 2.5 slots)

5770 1gb apple stock (pci e slot 3)

my system is
5,1
X5690 x 2
96gb ram 3 16gb ram slots in each processor

and here my link speed benchmarks of opencl ocean wave 1.61 attached

with only the rx 580 my speed is 3gb speed and
with the 2 gpus it drops down to 1.5gb

Why does it drop down to 50% with 2 gpus?

i have tried the configuration of

rx 580 slot 2
5770 slot 1

Same bad results.

if you know how to fix this it will be awesome
thanks!