Ok Guys, I'm Back and have a 2500k

[Quinetiam]

My definition of OCing I guess is different than many, because I want 24/7 stable and cool.

For example I have a 2500k at 4.4ghz that gets 7 on Cinebench 11.5 the same as a stock 2600k.

So it probably would not benefit me to get a 2600k even when OC'd it only gets 9 on Cinebench 11.5

A stock 3930k gets around 11.

In my situation with 3D rendering, 2x 2500k or 8150 systems would offer more render power than a 3930 or 3960 rig.

eVGA has that new SR-X XEON Dual socket mobo, too bad it's $650.

[Chike]

Neither passing IBT not not passing it means stability or instabilty, you can easily pass IBT and fail Prime95.
In no way any normal use of your PC wil produce so much heat as IBT does, and rarly reach Prime95 temperatures.
Prime95 is perfectly sutable to test the system with high probability of stability (stability is never guaranteed by any software).
Rendering won't get to temperatures high as Prime95.

As of Cinebench results I don't believe half of it, at best 2600K will do 20 percent better than 2500K. Don't believe anything you haven't seen in your own eyes or at least on what looks like reliable video.

What score did you get from the FX-8150?

Ypu worried about Xeon board price, what about the CPUs?

[Quinetiam]

FX-8150

Stock Cinebench 11.5 about 6.

OCd about 8.

FX-8150 felt faster than 2500K both stock and OCd in both 3D render and viewport modelling.

[Chike]

It is definately not faster, his 8 cores can barely win with 4 intel cores.
Though if rendering is your need you have probably should have stayed with it for both price and performance.

[Quinetiam]

I can only talk from my own experience in Vue 9.5 and Cinema 4D 11.

When rendering at 1920x1080 or Full HD with complex scenes with ambient occlusion lighting the FX-8150 is better than stock 2500k or 2600k.

On the other hand when using Photoshop or After Effects the i7 wins.

But one huge drawback of the Bulldozer is heat and noise, even at stock speeds.

I got a Asus Sabertooth and OCd the FX-8150 to 4.5ghz with a Corsair H80 and it was fast, but way too hot and hence very noisy.

[Chike]

The H80 is noisy as I hear, or maybe you had one of those that are more noisy and need moding.
Did it get very hot even at normal work?

As you can see there are no way to get around the core count, if you want Xeon that has 8 cores you have to pay over twice per core then you pay for 2500K or even more if it's FX-8160 core.
So maybe 2 systems are better, depends on your work flow. Perheps the 2500K and FX-8150 or 2600K. Of course 2 computer systems create double the noise of one.
But I used to work with Xeon P4 servers and those and those systems were not meant to be near humans, they were noise and had room of their own.

[Quinetiam]

The eVGA SR-X and other such 'consumer' XEON mobos look like a good option.

I'm thinking of the upgrade path where I can start out with a couple of cheap E5 Xeons and eventually upgrade to Two 8 cores cpus.

Even Two E5-2603 Xeon($200 each) should have similar rendering performance to a 2600k and of course a lot more memory bandwidth

[Chike]

Tou think a 1.8GHz CPU can do what 3.6GHz CPU can? Think again.
Benchmark Results: Rendering : Intel Xeon E5-2600: Doing Damage With Two Eight-Core CPUs
If 2 3.1GHz CPUs 8cores 16 threads each do 25.56 with Cinebench 11.5, one would do lets say 13.
Now we know HT help a bit so 8 cores without HT will do 10 percent less, 11.7, 4 cores half 5.85 clock it down to 1.8 and you get 3.4.
Still interested?

[Quinetiam]

I can only find Passmark scores for dual-E5-26xx series.

Dual E5-2609 score around 9500, the same as a 2600k.

[Chike]

So 2 390USD CPUs can do what a 340USD CPU can, does it look like a good deal?

I am quite confident my Cinebemch predicion is what the ES-2603 is capable of or above it. If you wish to throw money just to prove me I am right than go right ahead :)

The Xeon processors are made not only for cputing but to handle a lot of I/O and that adds extra cost for something you dont need.

I will add to what I have said before, there is no way around the cores/performance/cost.
Your system is about cost effective as it can be with Intel CPUs, if ou need more power and willing to pay for it that's fine of course.