Crossfire 5850, first impressions from a multi-GPU noob

[d_brennen]

First time I have used CF myself, after years of reading about the pitfalls of CF installs I've put it off. Having owned a 5850 since launch it was only just becoming a little lacking for me. Still an awesome performer considering it's from late 2009! Decided to bite the bullet and get another for CF as the 69xx cards don't really look like good value from where I'm sitting

My setup

Screen: Dell S2409W 1920x1080
PSU: 700w OCZ ModXstream
CPU: Phenom II X6 1055t @ 3.5GHz (does 4GHz but I like a quiet idle and can't get C&Q working at that clock)
RAM: 4GB DDR3 1600
GPUs: 2x reference 5850s (one ATI branded, one Sapphire, physically identical bar sticker, 775MH/1100MHz for now)
Motherboard: Asus M4A89GTD Pro
Case: Fractal Design XL, 3 x 140mm fans/1 x 120mm fan / 1 x 200m roof fan, all low speed

With much trepidation I plugged in the second 5850, power connectors and CF bridge. Powered on the computer and nothing on screen then as I realised that plugging in the monitor would help!

Arrived on the Windows 7 desktop in low resolution with Windows trying to install the second card. Dismissed the prompts and went ahead and installed a copy of Catalyst 11.8 on top of my current 11.8 preview drivers. Install went without a hitch but did have a couple more butt clenching black screen moments than a single GPU install

Rebooted, went into CCC and enabled the CF radio box, and that was that Tried a few games from my collection and with the exception of DE:HR (which ran ok before, bar the freezing and crash to desktop I will save that until it is fixed) and GTA4 I am very impressed. BFBC2 runs at well over 120FPS most of the time and I have upped some settings like AA too

Noise wise I am very impressed. My system is no louder than before both idle and under load. The spacing on this board means the cards are only ~6c apart in Afterburner under gaming load for a couple of hours

Anyway, don't know why I posted this, twiddling my thumbs before BF3

 

[d_brennen]

Yeah i did add the bridge as I wrote above took that pic just after plugging the card in. You'll also notice the fans are stationary, I added electricity too

 

[d_brennen]

Can confirm, two bridges don't make a difference

 

[d_brennen]

Are people looking at afterburner for their VRAM usage figures? Just an FYI when I played Crysis before installing CF it showed 600+MB VRAM usage and 1200+MB after...

 

[d_brennen]

Seems BF3 is using about 900-950MB (~1800MB as reported by Afterburner) at current settings i'm using. Haven't really fiddled. Fell through the floor a good few times just now, worrying number of bugs tbh. The game is finished for all intents, massive multi-gigabyte day 1 patch?

Frame rate is very high but I've been getting loads of lag spikes and pausing. Going away to the wifes sister for weekend, gutted

 

[d_brennen]

That does sound like the symptoms of vram or dram ram paging. However, at this stage of the game's development, it could be down to anything really.
It's not worth trading out a pair of 5850's at this point in time; for the most part they'll be as quick as any large single gpu available. Not much choice but to wait for the next gen...

Everyone's so obsessed with VRAM Figures 5-15 second pauses and lag (banding) are not caching issues

 

[d_brennen]

Any sources to say this is the case? How come the pausing/stuttering stops when I lower the shadows to low and turn off AA then? I'm sure its a VRAM issue and I only play at 1680 * 1050

Established my own source When playing with CF enabled I sometimes (though not last night but a lot tonight ) get loads of random pauses, FPS dropping to 1-5 for several seconds, pauses on the respawn screen and most annoyingly when close up and personal with the enemy. With CF disabled on one 5850 I don't see any of this behaviour, though much lower average FPS obviously

 

[d_brennen]

So its a driver issue? or maybe because this is a BETA

Well obviously this is a beta, I am only sharing my experiences Have you tried running 1 5850?