I'll test it the next time I reboot (I rarely reboot).

Since HT isn't useful for mprime, the only advantage of i7 compared to i5 is the extra 2MB L3 cache (8MB vs 6MB). [B]Is the 8MB cache useful for prime?[/B] or should I expect the same performance from an i5 for the same overclock? But since the difference between i7 and i5 is about 100 EUR I think it probably doesn't worth it...

Since the machine achieves 0.018s per-iteration time on one core, I think the 0.023s speed on 4 cores must be due to the memory bandwidth not being enough to feed all cores... So I'll try to see if I can put faster RAM on it!

The motherboard supports 2133 RAM, the highest I can find is DDR3-2000 RAM and the CPU officially goes up to 1333 (but works OK with my 1600). [B]Is there anyone here running i7-2600 (non-K/non-E/non-X) with the RAM set at 2000?[/B]

[B]Suggest me a worthwhile RAM upgrade for prime?[/B] I've 16GB of DDR3-[B]1600[/B] at [B]8-8-8-24[/B]. I can either give 260 EUR for the same amount of DDR3-[B]2000[/B] at [B]9-11-9-27[/B] or 240 EUR for DDR3-[B]1600[/B] at [B]7-8-7-20[/B]. What's better, higher bandwidth or lower latency?

When I buy a new CPU I'll keep this i7 with a cheap mobo and some RAM as a second computer, for prime, etc (to replace my aged P4-3.4). For the next CPU I can either get an i5-2500K (or the new Ivy Bridge i5) and a better cooler to overclock it as much as possible (people say it goes up to 5GHz, I think I can expect 4.6-4.8GHz with my air flow, I've got 9 fans but they're low-RPM), or wait to save money and get an SNB-E 3820 with a new mobo (which has quad-channel RAM) which I think goes up to 4GHz. [B]Would a dual-channel i5 at 4.8GHz be faster than a quad-channel i7E at 4GHz?[/B]

Here is a benchmark of a stock 2400, a stock 2500k and a 4.3GHz 2500k:

HP-NEW 2011-11-13 Intel Core i5-2400 @ 3.10GHz Windows64,Prime95,v26.6,build 3 [B]3143[/B] 10.78 14.04 17.05 20.71 23.04 29.03 35.75 42.89 47.34 3.35
Main 2011-12-01 Intel Core i5-2500K @ 3.30GHz Windows64,Prime95,v26.6,build 3 [B]3356[/B] 10.32 13.19 16.21 19.67 21.40 27.35 33.48 40.64 44.57 3.13
Main 2012-02-17 Intel Core i5-2500K @ 3.30GHz Windows,Prime95,v27.2,build 1 [B]4251[/B] 5.06 6.48 8.12 9.52 10.61 13.51 16.71 20.18 22.79 2.47

The 4.3 data is from 27.2, which was about 20% faster than 26.6, but you can see the improvement over stock.

[QUOTE=emily;290128]cores 1 and 4 are 62-63 C and cores 2 and 3 are 65-66 C.[/QUOTE]
so, you have a v-type heatpipes fan, haven't you? :P (that is usually 2-3 degrees colder on the side where the air goes in, at the "opening" of the "V", and hotter at the "tip" of the "V". That became my case too after I changed the standard i7 fan to a coolermaster V6gt, I even measured the temperature of each heatpipe, and the heatpipes at the opening of the "V" are always colder then the others.

It's a CoolerMaster Hyper 612S cooler with one 120mm fan on the side blowing air out. On the side there is the RAM which gets far too hot. Above the cooler there are two 140mm fans blowing hot air out.

So maybe it's hotter on the RAM's side and cooler on the side with the fans.

But I know I didn't apply the thermal grease as good as I could. :'(

The temps depend on the room temps of course, right now it's 59 C - 62 C. But the same cores will always be hotter than the others.

New question: the i7 has 8MB lf L3 cache shared with the Intel GPU. I use a discrete GPU, but if I switch to the Intel GPU for my Compiz GNU/Linux desktop will this slow down MPrime due to less cache available to the CPU cores? (since it would be used by the GPU) How much L3 cache does the Sandy Bridge Intel GPU use? I assume that when using the discrete GPU, the Intel GPU doesn't eat up any cache memory, right?

Why would you switch to the I HD G? It's crap.

Did you try Googling it?

Edit: [url]http://www.bit-tech.net/hardware/graphics/2011/01/27/intel-hd-graphics-3000-performance-review/3[/url]

Hey thanks for the link, it looks like L3 cache size doesn't matter much. I should google before asking...

There are some advantages of using Intel HD Graphics 2000/3000 compared to a discrete GPU:

1. Lower power consumption and less heat generated inside the chassis / better airflow
2. On GNU/Linux OS, able to use the Intel drivers.
3. On Windows OS,[B] able to use Quick Sync for video encoding[/B], which is very fast and also high-quality. This is probably the reason most people consider using Intel HD graphics.
4. Able to use the discrete GPU on another computer without spending money to buy a second discrete graphics card :)

And a few disadvantages:

1. No GPGPU tasks, at least last time I checked there wasn't a driver for OpenCL on SB.
2. Output only to two monitors instead of three or four.
3. Slow performance, barely playable 3D games
4. Must use the Intel drivers :P

For me, I used i7-2600's HD Graphics 2000 initially, with two monitors. But LucidLogix Virtu (which enables dual-GPU usage) doesn't work on GNU/Linux and I wanted a third monitor and Intel couldn't support that (it will be supported in Ivy Bridge or Haswell), so I got Sapphire HD6770 Flex which provides output to three DVI/HDMI/VGA monitors (or four, if you use DisplayPort). For now I finished most of the work that needed three monitors, I don't play games on this machine these days, and some bugs in the open-source Radeon driver bother me a lot. I think this AMD card consumes about 10-18W of power in idle, which isn't much but if I can save it by switching back to Intel it can only be good. After all, AMD GPUs don't do LL tests yet...

IB IG (HD 2500, 4000) will support OpenCL.

Yes IB will have OpenCL.

Will someday GIMPSers be able to factor or LL on it?

We're probably closer from the day where it becomes [i]possible[/i] to run LL tests on the IGP, than from the day where it becomes [i]efficient[/i] to run LL tests on the IGP :smile:
I mean, LL tests on the IGP becoming more efficient (in terms of wall clock time and power consumption) than LL tests on the CPU.