X4 Ray Tracing - Optimal CPU

[marty]

I had a look on line and it seems 4.5Ghz to 5Ghz is easily achievable with the i7 2600k
http://benchmarkreviews.com/index.ph...&limitstart=14

[Ian Pellant]

Marty,

Dare I ask you to run the test plan ray trace on your computer; then overclock it and see what the difference is?

Thanks.

[jpremodeler]

Marty,

Dare I ask you to run the test plan ray trace on your computer; then overclock it and see what the difference is?

Thanks.

I had a tough time at 5.0 keeping stable. I am air cooled, and my ram config only let me use 1 fan on my heat sink. If you can keep the 2600k stable at 5.0 with air, hat's off.

I did not benchmark my pre/post overclock, but it was a decent bump in speed. If I burn the cpu in a year, the time saved is worth it.

[Ian Pellant]

Overclocking....

I'm applying OC to my old P4 3.6GHZ.

It lives in a Shuttle that has a liquid cooled heat pipe system.

Results so far:
No OC 200: 17:16 CPU temp + 0C
OC 210: 16:27 CPU temp +1C
OC 215: 16:03 CPU temp +1C

Becoming interesting. CPU is running at around 3.9GHz and the performance boost is noticeable.

Currently running a test at OC 220 (frequency boost by 10%)... fly or fry?

The CPU normally runs flat out at 71C. Intel throttles it down at around 90C (Those old Prescott processors were designed to run hot). Seems I have a lot more OC headroom.

Cheers.

[jpremodeler]

I run at 71-73 C during raytracing with air

[Ian Pellant]

... went back to the Intel web site and found the white paper for the P4 660 series. (It is 6 years old, after all). It was designed to cut in throttling at over 73C. I'm on the edge.

OC over 4GHz and Chief ray tracer starts failing. It may be CPU temp throttling.

Seems stable at 220 (3.94GHz) which cuts the test ray trace to 15:43. Shaving almost 2 minutes off the time.

Studying the fan speed settings to see if the CPU temp can be brought down a bit.

Cheers

[marty]

Hi Max

Where I notice the increased speed on a daily basis is moving around elevations and cross sections which now move instantly without the lag which has always been there.

Your time of around 4x for a raytrace seems ok at that small scale but increase image size and/or resolution and a 30 minute job for me bexomes 2 hours for you. I cannot accurately measure a final image with shadows for the test view as it is too fast - somewhere between 1 and 3 seconds.

Of course the next version of Chief will use more resourses and we will be back to the beginning!

[Ian Pellant]

marty,

Same type of result that we got on an i7...

It is very good to see that late model machines are showing speed improvements.

Except for ray tracing my old P4 is fast enough with Chief X4 for any normal production purpose. (I'm modeling single storey houses, not commercial buildings with Chief.) Ray tracing bogs it down.

We bought the i7 only 3 months ago and it tests at around 1:40. That's a "professional business" computer from TechBuy.

The Xeon takes more like 13 minutes (it's a 3 year old HP workstation). It contains two sessions of the ray tracer, one within each core and does not cross-thread.

The difference between the Xeon and the consumer i7 series is a surprise. The CPU core is believed to be from the same design series.... but obviously the core to thread design is very different. The Xeon I am sitting in front of reports that it has 2 cores, 2 threads... and according to the latest (aka downloaded today) Intel CPU ID Utility, the Xeon does NOT support HyperThreading Technology. Ummmm... the threading model is what lets the i7 down in a consumer CPU. (Xeons are marketed for server and high performance workstations.)

Which still leaves me with the big unknown:
Does the AMD FX8xxx series handle cores and threads more like the Intel Xeon or the Intel i7 ?

I am beginning to suspect that the AMD FX8xxx is more like the Xeon... but I'l never know until it's tested in two session mode.

Cheers.