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Mixing Crossfire and water

combatus

Posted in Antony Leather, Watercooling, Hardware on February 21, 2008 at 12:01 am

Mixing Crossfire

I came accross a rather interesting article over at Legit Reviews which shows that as of the last couple of Catalyst releases (certainly after Cat 8.1) it is now possible to mix certain cards in Crossfire. Namely, as per the review, ATI’s latest mid range cards, the 3850 and 3870. With the introduction of  Crossfire X you may even be able to mix even more cards - say a 3870X2 and a 3850 etc etc. Very interesting stuff and the performance is pretty good too, especially with Antialiasing enabled - frame rates are doubled over your average 3850 in games like COD4. Whether it’s worth forking out for two cards at once is another matter - it’s usually more sensible financially to sell your old card and get a newer faster single card. But in my case, it was cheaper to get a 3870 and go Crossfire than to say, sell my 3850 and opt for something like an 8800GTS 512MB. Seeing as both setups can’t run Crysis but can cope with anything else , 3850 owners with Crossfire motherboards may want to consider a 3870, especially if new cards like the 3870X2 and 9800GX2 can’t run Crysis at your monitors native resolution on high settings.

The Decision…

With next gen graphics cards seemingly being delayed all over the auction and with ATI’s 3870X2 not puting a massively convincing arguement for spending £270 odd quid, I decided I needed to do something about my lonely 3850 which suffers badly at 1680×1050 when enabling AA. I had first thought about getting a cheap 8800GTX or 8800GTS, but both were close to or more than £200, certainly in the case of the GTX. However after reading the review I was warming to Crossfire seeing that it would give similar if not better performance to the latest cards from Nivida but would cost me less -  and when I found a 3870 for less than £120 in my local PC shop I grabbed it.

Crossfire miss-fire?

Now, for those who have read my forum post,  I had problems!!! the 3870 branded as  “Triplex” was far shorter than my Sapphire 3850 -  a bit odd and it looked like it was missing a whole row of voltage regulators! . It also didn’t come with a Crossfire bridge connector - not a big problem as my Sapphire did but many people use two and you need to for high resolutions.

I could enable Crossfire and got a stonking 15100 points in 3D Mark 06 at stock settings - even with my 3850 clocked as high as it would go I could only just about crack the 10,000 mark. I couldn’t compare the system to anyone elses on 3Dmark as apparently I’m the ONLY person with this setup! he he!!!  This could be the only watercooled 3870/3850 setup in the world!!!  

However I was unable to overclock the cards. In Catalyst Control Centre the sliders would move but on testing or running Autotune, the frequencies would return to default.  I tried reverting to Catalyst 8.1 but still no joy. In the end I decided to take the card back and low and behold my retailer had no idea the Triplex cards didn’t come with a Crossfire connector. While he was shouting down the phone at their supplier I was given a refund and decided to give a Sapphire 3870 a go - maybe running the same vendor would do the trick. I attached the second Crossfire connector as well and low and behold I can now overclock each card seperately!!! Woo hoo!

Just add water…

Now, something that has bugged me when overclocking my 3850 is that the cooler can’t handle much heat. In fact I’ve come out of games suffering from artifacts even though CCC overdrive passed the overclock, to find the card running in excess of 70′C!!!!  I used Rivatuner to create a fan profile to manually raise the fan speed but this didn’t always kick in and to run the fan at 60% speed which was needed to keep the thing cool was too noisy for my liking.

So too much noise and heat and Combatus is involved - you guessed it! Watercooling! Two EK Acetalfull cover blocks were soon at my door.

It won’t fit!!!!

 I started by removing the HSF from each GPU which was fairly easy. I fitted the 3870 waterblock but when I went to install the block on the 3850 —Horror!!!! It fouled one of the capacitors!!!! No matter how much I squeezed the block in, the holes for the mounting screws wouldn’t line up.

There was only one thing for it. Out came Mr Dremmel and a circular sanding block and I made a small groove in the copper so the Capacitor could fit recessed into it without actually touching the block. Not something you should have to do…

On the 3870 for some reason this capacitor is absent but with the block installed you can clearly see how much it fouls the capacitor placement.

The block now fits fine and also cools the voltage regulators but I’ll be on the blower to EK if they don’t know already! Without a dremmel this could render many blocks useless.

This is the first time I’ve installed dual card watercooling. Not for the faint hearted! I ended up with with the following loop:

Pump>GPU1>GPU2>RAD>CPU>RAD>Chipset/RAM>Reservoir

Amazingly the flow rate didn’t appear to be effected at all (EK blocks are fairly low restriction) and my CPU temp has only gone up a few degrees, although my system was designed around a CPU,GPU,Chipset/RAM to begin with - my watercooled X1900 died last year and the 3850 has been aircooled since then so there has been plenty of redundancy. I am probably going to re-hash the plumbing at some point, for cosmetic reasons if anything - it’s all over the place!

 Does look nice though….

 Overclocking…

So, now that overclocking is enabled and the cards are watercooled and running at a nice cool 30′C idle (down from 50+!)  it’s time to try a little clocking. I started by overclocking the 3850 to a modest 710Mhz/1020mhz up from 669mhz/829mhz. This gave me an extra 400 points in 3dmark 06 - 15498 and I know it can go a bit further too. Overclocking the 3870 was a different matter. The card refused to run 3Dmark 06 at anything other than default speeds. I’m sure the card can be clocked more than this but  it’s probably because it’s working as the main card in the setup - bit of a shame but future drivers may sort this and it’s amazing you can use the two cards together anyway!!!

So if you’re thinking of mixing Crossfire, firstly avoid the cheap Triplex cards, secondly try to use cards from the same vendor ie Sapphire. It’s also worth using both Crossfire connectors too!

Raptor futuremark multiplier Motherboard Mixing Crossfire cards Radeon asus blitz HD3850 multithreaded Unreal Tournament 2004 Hard Drive watercooling Serial ATA ATI E8400 PDA Blog ATI X1900XT MDA Vario III 2900XT Ipod ATI 4870 XP AMD SATA SLI Crossfire nvifia GTX 280 3Dmark dual core WCUK HTC TyTN II ATI 4850 High Definition HD blu-ray HD-DVD watercooling matrix HD3870 gaming Flash memory 8800GT Western digital CPCFF GPS 8800GTS windows Dual Graphics cards quad core Unreal Tournament DX10 msi x38 Crysis Graphics card Custom PC windows mobile 6 Flash Drive vista Hitachi Unreal Tournament 3 Nvidia cod4 Nokia N95 Symbian all in one device E8500 x38 chipset

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