3DMark 2006 Score with Quad 3870s?

[Ptaltaica]

Hi all; first of all, apologies for the long post. Anyhow.

I just put together a new system consisting of the following:
-ASUS M3A79-T Deluxe (790FX/SB750)
-Phenom 9950BE
-8GB OCZ DDR2-8500 (4x 2GB)
-Sapphire HD3870/512MB GDDR3 (x2) (Catalyst Control Center v8.6 for debugging)
-PowerColor HD3870/512MB GDDR3 (x2) (GPUs are installed with the Powercolors in the top & bottom slots and the Sapphires in the 2 middle slots, not that it matters; the crossfire bridges are connected to the connectors closest to the slot covers on the top and bottom pairs of cards and, obviously, on the "inside" pair of connectors between the two middle cards)
-Auzentech X-Plosion 7.1 Cinema sound card w/TI OPA637 opamps
-2x 1TB Seagate 7200.11s
-PCP&C 1KW PSU
-Vista Ultimate (OEM, 64 Bit)
-Nothing overclocked (yet)

I know that quad crossfire with the 3870s is an odd, objectively subpar choice when compared to a pair of 4850s or something, and I know that the Phenom is totally outclassed by Intel's current hardware, but I didn't build this thing to be the ultimate gaming machine. I built it because the 3870s were cheap, I haven't played with crossfire or Vista at all, the last AMD CPU I owned was a s754 Sempron 3100, and I was really, really bored. I could've had faster for the same money, but I already have faster systems than this (at least CPU wise), and I just wanted something different.

Now that it's running though, I'm not convinced that Crossfire is working properly. It's enabled with all 4 GPUs in the control center, but when I start GPU-Z it says that the 3rd GPU has Crossfire disabled, and I don't think my 3DMark 06 score is what it should be. With 4 way crossfire enabled, I'm getting 14107 overall, with a SM2.0 score of 5131 and a SM3.0 score of 7449. With Crossfire disabled I'm getting 11055 with SM2.0 and 3.0 scores of 4412 and 4775, respectively. I've also noticed that neither of the bottom two GPUs seem to be getting very warm at all-nowhere near as much as the top two. And only two GPUs show up in AMD overdrive; 3 & 4 are blanked out.

I'm at a loss here; I tried the 8.10 drivers and had these issues, so I did a clean install of Vista using the 8.6 version after reading a post on AMD's forums that quad crossfire is broken in the 8.7+ drivers. I've played a bit with various BIOS settings but that hasn't gotten me anywhere either. At this point I don't know what else to try short of pulling cards and swapping them around... I've been out of the loop more-or-less since the i875p and the 6800 Ultra were cutting edge; I built myself a dual quad core xeon "toy" earlier this year, but other than that this is my first serious build since probably 2004, so yeah... If anyone has any suggestions, I'd appreciate it.

Thanks.

 

[Dadofamunky]

3DMark 2006 is obsolete. Use 3DMark Vantage instead. That is outrageous. FOUR HD 3870s? Man.

 

[pcslookout]

Originally posted by: Dadofamunky
3DMark 2006 is obsolete. Use 3DMark Vantage instead. That is outrageous. FOUR HD 3870s? Man.

I wonder what he gets in Crysis at 1680x1050 with all details on very high in DX10, 4x AA and 16 AF with minimum and average framerate ? Like the ice levels and when fighting the boss. :Q

 

[error8]

Originally posted by: pcslookout

I wonder what he gets in Crysis at 1680x1050 with all details on very high in DX10, 4x AA and 16 AF with minimum and average framerate ? Like the ice levels and when fighting the boss. :Q

Not much, because you see, he has only 512 mb of Vram as a frame buffer and that can't be a good thing for high levels of AA. Crysis gets over 1 gb of Vram on the highest settings and probably this is why all the videocards out there chokes with it.

A 3870X2 has 512 mb for each GPU, but the memory is mirrored, what one has inside ( textures, shaders and so on ) the other one has it too. This is why ATI opted for 2X1024 mb for their 4870X2, to have 1 gb of frame buffer.

So 3870X2 in quad crossfire, even if it does have theoretically 2048 mb of Vram, it's only 512 mb since all those other 3X512 of memory are just a mirror of the first one and have the same data in them. This is the major disadvantage with multi GPU setups in my opinion. You have a lot of GPU power, but not enough ram to make use of it. This and the driver support.

 

[pcslookout]

Originally posted by: error8

Originally posted by: pcslookout

I wonder what he gets in Crysis at 1680x1050 with all details on very high in DX10, 4x AA and 16 AF with minimum and average framerate ? Like the ice levels and when fighting the boss. :Q

Not much, because you see, he has only 512 mb of Vram as a frame buffer and that can't be a good thing for high levels of AA. Crysis gets over 1 gb of Vram on the highest settings and probably this is why all the videocards out there chokes with it.

A 3870X2 has 512 mb for each GPU, but the memory is mirrored, what one has inside ( textures, shaders and so on ) the other one has it too. This is why ATI opted for 2X1024 mb for their 4870X2, to have 1 gb of frame buffer.

So 3870X2 in quad crossfire, even if it does have theoretically 2048 mb of Vram, it's only 512 mb since all those other 3X512 of memory are just a mirror of the first one and have the same data in them. This is the major disadvantage with multi GPU setups in my opinion. You have a lot of GPU power, but not enough ram to make use of it. This and the driver support.

I forgot about that. Has to suck.

 

[Ptaltaica]

Thanks for the info guys. I'll give Vantage a shot and see what difference it makes when I have a chance to deal with it; other than that I think it's probably going to come down to pulling the cards and reinstalling them one at a time while benchmarking it. Alternatively I could just give up and run F@H on them, I suppose, since I'd planned on doing that eventually anyhow... but it'd be nice to get them working the way they're supposed to work first.

 

[Dadofamunky]

Yeah, the memory scaling in Xfire (and in SLI) remains a real problem. Amazing design flaw, common to both types.