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Author Topic: Core i7 or Core i5 for a jrmc server streaming video to >1 gizmo/jremote client?  (Read 4377 times)

mattkhan

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My main jrmc server currently has a Core i3 4340 in it, this can't really handle being used as the primary HTPC (watching a BD) and streaming another (BD) film to a gizmo client. Both streams are intermittently a bit glitchy due to, as far as I can see, the CPU load.

I could swap the i3 for a core i5 4570 from another machine or I could buy an i7 if that is going to make a meaningful difference to sustainable performance. As far as I can see transcoding is a CPU intensive activity so the benefit of hyperthreading would seem quite limited.

Any views?
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mwillems

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The conventional wisdom is that for every bluray quality 1080p stream you want to be able to transcode separately, you need 2000 passmark points, plus some extra cpu room for any additional load you plan to place on the device (i.e. local playback).  My own experience has mirrored this; the i5 vs. i7 question isn't the real question, as there are modern i5 processors with much higher passmarks than some modern i7's (U-branded chips, etc.).  The clock and TDP are more important.  I have two i5s and two i7s around the house and my testing has suggested that the passmark method is a good approximation (give or take a stream).  

For your use case, you'd want a PC with a passmark above 4000, preferably into the 6's to give you some breathing room: that i3 should be able to handle two streams, it's kind of odd that it's not, but maybe local playback is more demanding in your case (are you using integrated graphics that might push down the CPU clock to stay under TDP?).  The i5 you mention has a 7k passmark, so should provide more than enough grunt for two streams, and could probably manage three as a pure server.

My five year old i7 2600K (8k-ish passmark) can handle three streams easily, and sometimes four depending on the content.  By contrast my new (as of last year) i5 nuc 4250U has a passmark below four thousand and struggles with transcoding more than one stream.  But there are U branded i7's (like the one in the new i7 NUC) with lower performance than your i5.

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mattkhan

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I should have been more specific, I am talking in terms of traditional desktop processors when I say i7 so something like a 4770.

The i3 is paired with a 660 GTX so no igp involved, it does handle an 11 path convolution filter that runs at (IIRC) about 6x real time so maybe that tips it over the edge.

It sounds like the extra headroom of the i7 will be useful to me based on your metrics.
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mwillems

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The i3 is paired with a 660 GTX so no igp involved, it does handle an 11 path convolution filter that runs at (IIRC) about 6x real time so maybe that tips it over the edge.

Yes if it's running at 6x realtime that would eat some CPU cycles!

Quote
It sounds like the extra headroom of the i7 will be useful to me based on your metrics.

Yes, I think so.  I have an i7-4790K at home (11k-ish passmark) and real-time transcoding of a single high quality 1080p file shows about 12 to 18% CPU utilization depending.  I haven't tried torture testing it with multiple streams as it's my gaming rig not a server, but that usage is loosely consistent with the formula.  
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mattkhan

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I swapped the i3 out for an i7 4790 today. After some BIOS related snafu (note to self; don't try to swap CPUs headless, check the BIOS supports the CPU before you begin), I had it running and it can handle 3 concurrent bd streams without issues. A most pleasingly fast computer.
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mwillems

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I swapped the i3 out for an i7 4790 today. After some BIOS related snafu (note to self; don't try to swap CPUs headless, check the BIOS supports the CPU before you begin), I had it running and it can handle 3 concurrent bd streams without issues. A most pleasingly fast computer.

Sweet;  I love it when a plan comes together  ;D

I've got two of the 4790 family floating around (one "K" and one "S"), and I've been very happy with both so far.  They run a little hotter than the Sandy Bridge i7s, but the performance and energy efficiency improvements are well worth running an extra fan or two.
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