Hyperthreading on Quad-Core? i5-750 or i7-860?

I need to build a new computer for photo processing and other related tasks.
It will run Windows 7 Pro 64bit with 8GB of ram.

I'm looking at the two processors below:
Intel Core i5-750 Lynnfield 2.6GHz 8MB L3 Cache (4 real cores, no hyper-threading).
Intel Core i7-860 Lynnfield 2.8GHz 8MB L3 Cache (4 real cores + 4 virtual hyper-threaded cores (8 total)).

For all practical purposes, these processors are about the same speed, except the i7-860 includes hyperthreading which makes it appear as having 8 cores.

My question is: Can a quad-core processor used for RAW processing actually take advantage of 4 real cores, not to mention 8 HT cores? Also, would 4 real cores + 4 HT cores actually speed up RAW processing when compared to the same CPU with HT disabled?

Can you please make your font bigger, it's hard to read when you make it small. You want to make it easy for people to help you, not difficult, changing font size and style works against you.

I can't answer your question, but in general it seems to give a 10-20% improvement in overall performance. What i've read (and can't back up) is ACR scales well to 4 cores, but then improvement goes down, and i'm not sure if hyperthreading helps or not. Someone with an i7 could probably disable hyperthreading and give you a better idea. These links may help... or may not, they're not ACR specific.

http://www.hardwarecan​ucks.com …-processor-review-14.html

http://www.macworld.co​m …/2009/11/core15​_imac.html

Speculation: Real world performance probably won't be massively different. Memory bandwidth, disk speed, and cache size will probably mean you're not limited by RAW CPU power. I'd probably decide by price, and by which socket is more future proof (though socket may be the same - no idea).

John,

I think Tim is right about real-world performance. I'm not sure there's much of anything out there right now that can take *full*-advantage of the 4 core + hyperthreading of the i7. Not a huge shocker, since it's virtually always been the case that the top-of-the-line chips are so new that nobody's had time to utilize the latest and greatest in processing power.

The i5 is much better positionally priced at present. And chances are, you'd probably not notice any difference between it and the i7.

BeritOlam wrote in post #9106267
I think Tim is right about real-world performance. I'm not sure there's much of anything out there right now that can take *full*-advantage of the 4 core + hyperthreading of the i7. Not a huge shocker, since it's virtually always been the case that the top-of-the-line chips are so new that nobody's had time to utilize the latest and greatest in processing power..

Dead wrong here, especially in photography/video editing. LR2 will make full use of all cores and all threads when batching photos, and media encoder will do the same when encoding h264 or mpeg2. Right now there's a glitch where only a quarter to a third of the cores are used in OSX, but in windows, 100% perfect.

Under windows LR and LR2 will both use as many cores as you can throw at them, so yes, large batch RAW conversions will go a lot faster on an i7 with HT enabled.
LR processes each file as a separate thread, and windows simply gives it as many cores as it has free.
(off topic, but apparently OS-X Leopard has issues with LR. Leopard was never very good at multi-threaded apps on multiple CPU's, and when batching it would give all spare cores to the batch process, so doing anything else in LR was very, very slow. Adobe released a patch for LR that limits it use of multiple cores under OS-X to get around this.
OS-X Snow Leopard is supposed to much smarter, and should work perfectly with LR3 when it's released).


Most raw conversion software works in a similar way, so can also take advantage of multiple cores.
Of course you need a decent HDD and RAM set up as well, all on quality mother board, other wise your going to run into limits there (as Tim said) before you reach the limits of the CPU.
But, 8-10mb RAW files are small enough that you can use all 8 cores easily enough. Batching 2-300mb TIFF files might be a bit different.

Can anyone with an i7 disable hyperthreading and give a real world number?

tim wrote in post #9106213
Can you please make your font bigger, it's hard to read when you make it small. You want to make it easy for people to help you, not difficult, changing font size and style works against you.

I can't answer your question, but in general it seems to give a 10-20% improvement in overall performance. What i've read (and can't back up) is ACR scales well to 4 cores, but then improvement goes down, and i'm not sure if hyperthreading helps or not. Someone with an i7 could probably disable hyperthreading and give you a better idea. These links may help... or may not, they're not ACR specific.

http://www.hardwarecan​ucks.com …-processor-review-14.html

http://www.macworld.co​m …/2009/11/core15​_imac.html

Speculation: Real world performance probably won't be massively different. Memory bandwidth, disk speed, and cache size will probably mean you're not limited by RAW CPU power. I'd probably decide by price, and by which socket is more future proof (though socket may be the same - no idea).

Thanks for all of the replies. Sorry about the small font. I pasted some stuff into the post and the font got messed up. It seemed big enough in Firefox for me, but I forgot that I had already increased my font size in the browser.

I too would be very interested in someone disabling & enabling HT with a Core i7 processor and batching a stack of RAW files and sharing what they find.

John_TX wrote in post #9109920
Thanks for all of the replies. Sorry about the small font. I pasted some stuff into the post and the font got messed up. It seemed big enough in Firefox for me, but I forgot that I had already increased my font size in the browser.

I too would be very interested in someone disabling & enabling HT with a Core i7 processor and batching a stack of RAW files and sharing what they find.

VERY old article, but it shows you the power of even the older hyper-threading. Newer hyper-threading is a bit more mature, but still limited to the same issues ( luckily a lot of programs now work better, and windows takes advantage of it... just still gaming that lags behind).

Most filters in photoshop are RAM dependant, rather than CPU dependant, so they are not a good tool to show differnces in CPU performance.
They are a better indicator of bus speed and RAM performance.
If you run the photoshop benchmark in this forum with the performance monitor open you can see how the differnt filters, adjusmtents, layers etc, all use different elements of a computer.

I don't think anyone cares about filters, RAW processing speed and general photo manipulation is a more useful benchmark. People who benchmark love to use filters though, not sure why.

tim wrote in post #9110608
I don't think anyone cares about filters, RAW processing speed and general photo manipulation is a more useful benchmark. People who benchmark love to use filters though, not sure why.

Because they don't know how to make actions that replicate real users... like dodging and burning, painting, liquify, etc..

Hyper thread processors are just pretend they will only get used if the CPU resources are not being used so leaving them enabled (or having them) will not do much unless some new process needs the unused resources then those resources are available. I cannot see a down side to leaving it enabled (unless it causes some weird behaviour as with some very old DOS software). I do think that hyperthreading on my i7 works a whole lot better than it did on a single core machine and I figure that a quad core processor is more likely to have free resources that are needed than a single core may.

Now as far as choosing processor in my experience photoshop does not seem to use more than 4 cores very often (although it will occasionally) but memory is a much bigger issue. I give photoshop 10 GB of memory out of 12 and it grabs it all most of the time. When files go to swap they get big fast so I think everything is being written to the swap file and even a fast hard drive is a relatively slow device.

It seems to me that photoshop is a memory intensive application that needs processors somewhat less as opposed to an application that uses small amounts of memory, at one time, but using a lot of processing power. When configuring a photoshop machine that is my guiding principle.

Quad wrote in post #9111567
Hyper thread processors are just pretend they will only get used if the CPU resources are not being used so leaving them enabled (or having them) will not do much unless some new process needs the unused resources then those resources are available. I cannot see a down side to leaving it enabled (unless it causes some weird behaviour as with some very old DOS software). I do think that hyperthreading on my i7 works a whole lot better than it did on a single core machine and I figure that a quad core processor is more likely to have free resources that are needed than a single core may.

Has to do with the amount of cache allotted to each "core". If you play games, you know the more L2 and L3 cache your cpu gets, the better it will play. Check out the new athlon x4s and phenom II x4, they have the same cores, but phenom II has consistently higher scores (almost 50% higher in fact) because it has L3 cache. Some filters in photoshop may be the same, but for the most part the increase in overall speed by using it far outweighs having it off.

And no, the threads don't just sit there and wait, windows likes to even out the processing, so if you have one process taking up one core, it'll move other processes to other cores.

I think I'd buy the cheaper i5, which can also use a cheaper motherboard, and use the money saved toward a solid state drive.

Kent Clark wrote in post #9116920
I think I'd buy the cheaper i5, which can also use a cheaper motherboard, and use the money saved toward a solid state drive.

Wrong, i5 750 and i7 860 use the SAME motherboards. The i7 900 series processors use the x58 board design. But doesn't matter, since they use the same board, you can later upgrade to an i7 800 series if you find a need for it.