PCIE lanes 16/16 8/8 4/4

[2DividedbyZero]

I have a Rampage II Extreme mobo, I am interested in tri-fire 5970+5870

my mobo will run at 16x PCIE with 1 card installed and I believe both lanes will run in 8x when 2 cards installed


I have searched the internets and read a few worrying posts and wish to clear this up...

When just 5970 fitted on a 16x PCIE lane, the lane is split for both cores having 8x PCIE each
When 2 cards fitted and the lanes are 8x 8x, a 5970 will then further split the lane to 4x 4x per core???? Is this correct or are the internets wrong?

 

[2DividedbyZero]

well all may not be as bad as i thought

according to the asus site (select specifications) http://www.asus.com/Product.aspx?P_ID=W7i5W4Pw4fH22Mih
both lanes will run at 16x when 2 cards are installed, can anyone confirm this for me? cheers

 

[HossHuge]

3 x PCIe 2.0 x16 support at x16, x8, x8, or dual x16 speed

Like it says. In trifire 1st slot x16, 2nd slot x8, 3rd slot x8

crossfire 1st slot X16, 2nd slot x16


So your 5970 will still run a x16...

 

[erocker]

With two cards fitted it's 16 + 16

With three cards it's 16 + 8 + 8

 

[2DividedbyZero]

Like it says. 1st slot x16, 2nd slot x8, 3rd slot x8


So your 5970 will still run a x8...

but unfortunately the 5970 HAS to go in the second slot due to the Accelero Xtreme cooler when a second card fitted (in 1st slot)

but it says dual 16x, so does that mean both lanes run 16x with 2 cards?

 

[2DividedbyZero]

cheers erocker u posted whilst i was typing


(read that as "you posted whilst i was scratching my balls")

 

[Undead46]

It doesn't matter, x16 and x8 are so close together, you would probably see 1-3FPS difference between the two.

 

[Spectrum]

undead is right, check this out:
http://www.techpowerup.com/reviews/AMD/HD_5870_PCI-Express_Scaling/1.html

 

[2DividedbyZero]

yeah, my concern was - if a 5970 on a 16x PCIe lane ran at 8x 8x per core, then a 5970 on a 8x PCIe lane would run at 4x 4x per core (according to the internets)

now if it was so, that would be a big difference in speed no?

 

[Tatty_Two]

cheers erocker u posted whilst i was typing


(read that as "you posted whilst i was scratching my balls")

No, the primary slot is the only slot that will give you x16 when the secondary is populated, if your 5970 is in the secondary you will only get x8, however like others have said, there is not a great deal of difference, although the more powerful the card, the greater the difference but still very little.

 

[2DividedbyZero]

i wish there was definitive answer

can someone confirm this for me though =

if my 5970 was in a 16x PCIe lane, would each core take 8x 8x
if my 5970 was in a 8x PCIe lane, would each core take 4x 4x

if so, is it worth putting the card in the second lane(slot)? hence pointless going tri-fire?

or are both lanes(slots) 16x (as the asus site says)

 

[micropage7]

i wish there was definitive answer

can someone confirm this for me though =

if my 5970 was in a 16x PCIe lane, would each core take 8x 8x
if my 5970 was in a 8x PCIe lane, would each core take 4x 4x

if so, is it worth putting the card in the second lane(slot)? hence pointless going tri-fire?

or are both lanes(slots) 16x (as the asus site says)

i guess when you put 2nd or 3rd card it doesnt mean it will read by core, it doesnt mean if you have 2 cores on that it will run on 8x, from system it will read as one graphic card no matter how many cores on one vga, and how about the performance of each it return on driver and the chip itself
i guess like that. sorry if i made a mistake

 

[2DividedbyZero]

well, if/when i get a 2nd card, i shall run some tests and report back - hopefully the 5970 in the second slot won't be restricted. And despite what my wtb thread says, I want to put in a 5850 toxic - up clocks to 850/1200 to match the 5970 and hold my breath (for as long as the benches take that is )

cheers guys

 

[2DividedbyZero]

well

a little peek through my BIOS and I found the following information regarding slot#2 speeds, ACCORDING to the BIOS, slot 2 will be 16x as long as slot#3 is empty or x1.. well thats how I read it... take a look...

 

[de.das.dude]

i followed TPUs article on comparing gfxs on different lanes by taping shut a couple of connectors
may i know which connectors apply for the 1x slot??
i'll try a ghetto mod probably to try and run my 4650 in the 1x slot hehehehehe

 

[2DividedbyZero]

i'll try a ghetto mod probably to try and run my 4650 in the 1x slot hehehehehe

 

[erocker]

No, the primary slot is the only slot that will give you x16 when the secondary is populated, if your 5970 is in the secondary you will only get x8, however like others have said, there is not a great deal of difference, although the more powerful the card, the greater the difference but still very little.

Nope, it dual x16. Two populated slots are x16 each. Three populated slots are x16 + x8 + x8

 

[blkhogan]

Nope, it dual x16. Two populated slots are x16 each. Three populated slots are x16 + x8 + x8

Thats how Im reading it. 1 card = x16 / 2 cards = x16 + x16 / 3 cards = x16 + x8 + x8. Either way with cards of the level your dealing with, your actual seen output change will be small at best. Its going to be smoking fast anyway you set it up.

 

[Tatty_Two]

Nope, it dual x16. Two populated slots are x16 each. Three populated slots are x16 + x8 + x8

I didnt check the spec, he indicated that the 2nd slot was slower in the Op and was talking about whether the 2 GPU's of the 5970 would use 8 each in the primary.

 

[2DividedbyZero]

as i now have a 5850 toxic to tri-fire with my 5970, i CAN CONFIRM that both slots are PCIe x16 when populated



I can also confirm that flashing a 5850 toxic with the 5870 toxic BIOS DID NOT WORK :shadedshu but to my surprise, the 5850 default core voltage was 1.162v (expected 1.088v according to the internets)



I have bench tested and will post up tomorrow, but I will say that the only decent "big" improvement was seen in Unigen Heaven with 5970+5850.

5850 on its own was very good, but 5970+5850, well, i expected better. I guess games will prove better in the near future when released.

like I said, benches will be up tomorrow.

 

[2DividedbyZero]

well, if/when i get a 2nd card, i shall run some tests and report back

here I go.
Despite what i first thought, 3DMark11 and Heaven both showed good scaling imo.

3 tests run

3DMark11, 3DMark Vantage and Unigine Heaven

config

5850, 5970 and 5850+5970 (all clocks were 850/1200)

rig
(modest OC but i just want the cards performance figures)

i7 980X @ 4GHz
6Gb 1600MHz DDR3 6-6-6-18-48-1T
850W Cooler Master PSU
Asus Rampage II Extreme mobo BIOS 1914
F40 SSD, 2x 640Gb WD Black RAID0


screen shot of rig config:


TEST 1 3DMark Vantage

5850............ P20245 - GPU Score 17570
5970............ P32800 - GPU Score 31583
5850+5970... P38719 - GPU Score 39236

5970 gave a 79.7% performance increase (GPU Score) over 5850
5850+5970 gave a 24.2% performance increase (GPU Score) over 5970

screenies





TEST 2 3DMark 11

5850............ P4718 - GPU Score 4425
5970............ P8929 - GPU Score 8978
5850+5970... P12205 - GPU Score 13243

5970 gave a 102.9% performance increase (GPU Score) over 5850
5850+5970 gave a 47.5% performance increase (GPU Score) over 5970

screenies





TEST 3 Heaven 1920x1200

5850............ Score 889
5970............ Score 1758
5850+5970... Score 2615

5970 gave a 97.7% performance increase over 5850
5850+5970 gave a 48.7% performance increase over 5970

screenies



ignoring vantage and taking 3DMark11 and Unigine, the scaling looks spot on in my tests:

102.9+97.7 / 2 = 100.3% scaling 5970 from 5850
47.5+48.3 / 2 = 47.9% scaling 5970+5850 from 5970



CONCLUSION

Absolutely outstanding temps from the 5850 considering it is crammed up against the 5970 tighter than a nuns chuff, fan is "quiet" @ 57% max during tests and the 5970 fan is "inaudible"

yeah, I'm happy.

I know everything won't scale as well but it leaves me feeling hugs for my rig.




last note to re-iterate what I said in the previous post, the 5850 DID NOT flash to 5870 unfortunatley but it did have 1.163v as apposed to 1.088v, plus 8+6pin connectors, i thought these cards awere 6+6, can anyone else comment on this?

 

[2DividedbyZero]

heaven 2.1 v 2.5 benchies coming up...

 

[2DividedbyZero]

apart from looking exactly the same (to me) a few differences in scores


2.5 had a lot lower min FPS, and higher max FPS resulting in a higher overall score.


both test run at the same system config (currently GPU's 875/1225 and CPU 4.33GHz)


2.1 Scored 2717

2.5 Scored 2817 = 3.7% faster (for me)