AnyOne Out there running 3 HD4890s in TriFire

[Kensek]

My third Asus Top HD4890 which arrived DOA from Newegg in the middle of July came back from Asus yesterday.

I figured if 1 HD4890 running at 1000/1200 with an i7 920 running at 217x21 (4.56GHz) scored 23,500 in 3DMARK06

And 2 Scored 31,200 at the same speeds.

I thought 3 would score 34K.

Well I ran 3 of them in TriFire Mode in Vista 32-bit, Win7 32-bit and Win7 64-bit.

All 3 Operating Systems do anywhere from 32000-32130 in 3DMark06.

I take it that the third card really doesn't scale that well since I only benefit from a 3% increase in my scores from a 2 card setup.

I take it my CPU may be bottlenecking me also?

Or is running 3 cards at 16x/8x/8x hurting me also.

Any thoughts?

Thanx

[cky2k6]

I'd say its def a cpu bottleneck. Crank up the res and aa in 06, and you'll see the tri-fire setup pull away. of course, nobody really bothers with that, cause thats not the point of 06 benching, but just saying lol. btw, your two 4890s score a bit higher than my 4870x2 cf with my cpu at 4.5, my cards have zero oc headroom practically.

[nicspits]

I don't think '06 is a great benchmark for tri-fire, you'd probably see a greater distinction in Crysis 2 and so on, but yes, you definitely need to increase the load on the GPUs. Think of it like a ton of torque but you're pushing a light car, you can't get traction unless you load it down a bit :) I really don't think it's a cpu bottleneck but a really easy way to tell is drop the clock 100mhz and see if the score falls proportionately.

[perkam]

Here is an entire review of tri-fire and tri-sli platforms that includes HD 4890 and GTX 285: http://www.xbitlabs.com/articles/video/display/3way-sli-crossfire.html

Here are their results on 3dmark 06:

http://www.xbitlabs.com/images/video/3way-sli-crossfire/6dm_total.png

Your system is the fifth one from the top. As you can see, the difference in 3dmark 06 from crossfire to tri-fire is miniscule. The real difference comes in games:

http://www.xbitlabs.com/images/video/3way-sli-crossfire/grid.png

The difference can be seen in the highest 2560 resolution where tri-fire really shows its power as it barely takes a hit going from 1920 to 2560, unlike crossfire.

However, unless you game at that res, 4890 Crossfire is powerful enough today's games, tomorrow's games and probably games in 2012 0_o

Perkam