CrossfireX Behavior

Omophorus

Limp Gawd
Joined
Jan 23, 2009
Messages
146
Just a quick question for others here with CF setups.

When you're at the desktop, running windowed apps, etc. are you finding that the rendering load defaults to your primary GPU or the linked GPU?

The reason I ask is that I have one reference 5870, and one with stock clocks but not the reference cooler. I intentionally set it up so that the latter (a Gigabyte) would be the primary card, as it runs 10-15C cooler and seems to have less flaky VRMs. However, except when running full-screen games on my primary monitor, the primary card always sits idle and the rendering is always done on the linked card (including running windowed games on my primary monitor, which SHOULD be done by the primary card).

This is exactly bassackwards from what I want to happen, and certain applications have actually begun overheating the VRMs on my linked card to the point where I'm getting BSODs. The impeller on the card is dying to boot, so I can't just manually crank up fan speed to cool the VRMs like I used to be able to. The obvious choice would be an aftermarket cooler... except that it seems most of the 5870-compatible coolers are going EOL since AMD is no longer making the 5800 series.

Anyone else see similar behavior or have any success getting the primary card in the CF pair to be the default for rendering?
 

sirmonkey1985

[H]ard|DCer of the Month - July 2010
Joined
Sep 13, 2008
Messages
22,230
it could be what ever you are using monitoring it. also could be that your pci-e slots are reversed..

to give an example with both evga precision and afterburner and the nvidia drivers my primary card is registered as gpu 2 and my secondary GPU 1. screws me up sometimes when looking at gpu loads and keep thinking my second card is being loaded instead of the primary..

thats my guess in whats happening. because if you have the default settings in your CCC the second(non primary) card should be completely turning off when its not in use(not gaming).
 

Omophorus

Limp Gawd
Joined
Jan 23, 2009
Messages
146
Plausible, but I'm not sure.

CCC clearly labels the Gigabyte as the primary, registry shows the Gigabyte as instance 0000, and system information shows the Gigabyte driving the main monitor (1920x1200) and the Sapphire driving the secondary (1680x1050).

Then again, GPUz thinks the Gigabyte is the primary card, but has the sensors reversed (so it's showing the Sapphire sensor data when looking at the Gigabyte and vice versa).

Afterburner shows the Gigabyte as GPU1, but all the rendering is done on GPU2.

I tried popping the secondary GPU out and back in with Windows boots in between, but that did not ameliorate the problem. Guess I'll try flipping the two and see what happens.
 

sirmonkey1985

[H]ard|DCer of the Month - July 2010
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22,230
wait so you have the monitors split between the cards instead of both of them on the primary card only?
 

Omophorus

Limp Gawd
Joined
Jan 23, 2009
Messages
146
Both monitors are connected to the primary card, as they should be.

What is going on is that the secondary card is always the one used for rendering except in fullscreen 3D applications on my primary monitor.

The expected CF behavior is that the second card sits idle except when it can be leveraged as a GPGPU or for CF-enabled gaming. I am seeing the reverse behavior, with my primary card sitting idle.

I actually called AMD about it, and the poor T1 support guy could pretty much only say "that's not supposed to happen".

The T2 guy it got escalated to just said "we've never seen anything like this before, it's probably not our fault, go try to get all this fixed under warranty".

(Real easy to get a card that's been out of production for a while now fixed under warranty...oh wait)

It's possible there's something spazzy about my primary card, but I'm pretty sure it's a combination of the non-identical hardware and driver issue (except that the issue has persisted across every driver revision I've tested). I never have any rendering issues in-game when the primary card is actually running.

This wouldn't be as much of an issue were the TRad2 not out of production. I don't have enough space to install a 3 slot cooler, and I wouldn't even be that worried so long as I had decent cooling (especially for the VRMs). The combination of bassackwards CF behavior and slowly dying impeller on the secondary card is what's giving me heartburn.

Edit: Sysinfo to show what I meant about the monitors thing, note that this doesn't mean there's a DVI cable hooked up to the slave card.
15rm5gk.jpg
 
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sirmonkey1985

[H]ard|DCer of the Month - July 2010
Joined
Sep 13, 2008
Messages
22,230
weird..

other thing you could try just for shits and giggles and i'm sure you have tried this.. try hooking up the 2 displays to the secondary card, see if that card continues to be the card thats used or if it switches it to the other card.. i've seriously never seen that happen before. my only other theory is that the PCI-e slots are reversed on that board(not all that uncommon) and thus since the bios see's the secondary card as the primary slot windows/drivers may just be doing the same thing.
 

samuelmorris

Supreme [H]ardness
Joined
Dec 20, 2010
Messages
5,506
Afterburner always got it backwards for me. CCC typically tends to report it correctly.
 
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