Choosing a CPU

Hello, after some advice here. I'm speccing out a new PC and have a quick query.

Core 2 Duo? Or Core 2 Quad?

Core 2 Duo (E8500) 3166 MHz 6144 KiB 1333 MT/s
Core 2 Quad (Q9300) 2500 MHz 2 × 3072 KiB 1333 MT/s

These are the same price, both 45nm. Isn't the quad almost twice the speed? I'm confused - what am I missing here?

TIA!

I think it's as simple as do you want two cpus (core=cpu) that run at 3166 MHZ with a 6MB cache or four cpus that run at 2500 MHZ with two 3MB cache chips. If you want games go for less cores with more power (#1), if you want server/multitasking go for more cores (#2).

You're exchanging a lower clock speed for more "cores". Unless you're running an application designed to take advantage of multiple cores, or you are running several different processor-intensive applications simultaneously the Core 2 Duo will be about 20% faster for you due to the higher clock speed (3166 MHz vs. 2500 MHz).

If you *do* run multi-threaded applications that are specifically written to spread their computation across multiple processor cores, then the Quad will be considerably faster. Way faster -- assuming the computational task lends itself to be solved piecemeal. Engineering software like finite element analysis packages benefit tremendously from multi-core, as long as there is enough RAM to keep the process CPU bound.

What will you be using the machine for?

Edit: note that some games written to support multi-core are still bound by one computational thread and thus the extra speed of the 2 core system will actually result in higher performance than the 4 core system -- even though the program is written to take advantage of 4 cores the problem it is trying to solve is not well suited to this. Unless you have a numerically intensive application or are running a server, get the 2 core chip.

Ah right, gotcha. Lets say its for a media PC - HiDef video editing/playback. Blu-Ray DVDs, music/video streaming. No games at all. What would be best here?

Running on Vista Home Premium (MCE), 4GB DDR2 (or 3)

Edit: I'll be recording TV shows too (maybe 2 at a time) not HD yet though :-( but lets assume that OTA HD will be in the UK soon and I'll want to record that.

Thanks!

It would depend entirely on the particular software you were using to play back and record the media. Which software packages were you planning on using?

I'm guessing that most media playback software is *not* written to support multiple processors. I could imagine that some *recording* software might make use of multiple cores during the encoding process, but the software's specifications would need to state that explicitly before I bought the quad-core.

The quadcore should be best for that -- quicker real-time response etc.. when there are more CPU cores to distribute things over.

It does depend quite a bit on the operating system, too though.

My MythTV box (Linux) is on a dual-core (quads weren't available back then). The two cores mean it can playback HiDef 1920x1080i while simultaneously running a commercial stripping job. Each ends up using about 100% of a core, but with two cores no problem.

Four cores would be even better there, as it could then run multiple commercial stripping jobs simultaneously (we frequently record multiple things at the same time, each of which requires a commercial stripping job to eventually run).

The recording processes themselves require practically no CPU time at all (hardware Mpeg encoders), so four of those can be active while watching something else and doing the commercial scanning.

Cheers

The main MythTV decoders (MPEG2 etc..) are multithreaded so they do take advantage of multiple CPUs. Recording is a simple task anymore if you are recording HDTV, all you have to do is write the MPEG stream to disk. If you are still recording Standard TV you probably should think about upgrading to HD recording soon..

Now might be a good time to mention that I've been out of the pc game for so long that I was just planning on shoving vista on there and using media centre. I don't think I'm ready for Myth TV (yet). Using Vista, is there other software I need to consider? (Other than the BR playback)

I'm wondering would I use 4 cores? At *most* I'd be watching HiDef footage - either a ripped BR disc or playing a BR disc. At the same time I'd be recording something (maybe 2 things) on Freeview* or encoding.

If it was a dual core doing that would it be immediately obvious by stuttering the playback? I wonder does anyone know what the bare minimum requirement is for HD playback?

So lets ignore HD freeview for now and assume its SD for the next 4 years. If it was you, doing the above what would you recommend?


*HD Freeview is apparently planned for rollout in 2009. We have no OTA free HD content here (at least nothing that's commonly available). I see that the US shops sell HDTV cards - are they doing all their work in hardware? I want to future proof myself as much as I can although by the time its in common use (2012) I'll have a new machine anyway. Hmmm :S

The other option is that I just get a...

Core 2 Quad (Q9550) 2833 MHz 2×6144 KiB 1333 MT/s

Its twice the price but would this solve my dilemma?

Second issue is heat. This is going to be in the living room so I have thought about quiet cooling systems. Thing is, how much more heat would this pump out?

It takes 100% of one core on my 1.86Mhz Core2Duo chip. The rule of thumb on the net seems to be one 2.4GHz CPU for unaccelerated HD playback.

You must not be in mainland USA, or even Canada then. Probably in the UK(?). HDTV standards may differ there.


They don't have any work to do. The HD broadcast simply arrives as a pre-encoded MPEG2 stream with 5.1 surround sound, all encoded. Recording is literally as simple as cat /dev/decoder > /var/saved_this_broadcast.mpg, and takes less than 1% of pretty much any CPU.

-ml

First time around, I found MythTV too daunting. Too many pieces. More recently, using one of the tailored distros (MythDora) installation was much easier. Anyhow, if you are curious about that, it would probably only take about 30 minutes of your time to install MythDora before you go on to wipe it and install Vista....and activate it....and ....:)

http://www.mythdorawiki.com/wiki/index.php/Main_Page

For a multimedia box, definitely go for the quad. While you may not see a huge advantage one way or another with duo vs quad with some basic local use, the quad is going to allow you to scale more. For example, with Media Center, you can add extenders to be able to watch content off the main machine on another TV elsewhere in the house. Windows spawns a modified remote desktop process to support extenders, so with a quad, the process could take a full core, or even two without impacting the local machines ability to record and watch a show.

I love hardware and all, but I'm a grump about recent advancements. Can Windows really harness dual core, let alone quad? My new dual core machine merrily churns away at 50% CPU usage max; that's one core at 100%. I've only spiked a dual core using VMWare running a dual core 64 bit virtual machine.

I think hardware has so far outpaced software that there's no reason for quad and all that. Save the money.

But everyone else disagrees, more knowledgeably at that. Does Vista Media Center really use all four cores?? Maybe some optimized version of Linux, but Windows?

You have to have multiple processing threads running simultaneously to utilize multiple cores. A single thread can only run on one CPU at a time. Try running several video encoders at the same time.

Hi,

I perform alot of SPICE simulations and recently had to get a Quad core 2.66 GHz with lots of RAM.

The dual HT Zeon 3 GHz processor (2 separate CPUs) system was fast, but when simulations ran 10 hours, I needed more horsepower and RAM.

The quad core with more RAM ran 40% faster (read more simulations per day) and occupied the processors around 60%. If I run more than one concurrent simulation, I can get it up to around 85%. I also run this system separately, bare bones software, configuration, and it is not connected to the network to minimize housekeeping. My other system has everything running of course including full software, connectivity, simulations at night and background.

I have seen good luck with the quad, but, I've only had it for a month. There may also be a big kick from the extra RAM Core to run in too. It was a jump from 2 GB to 4 GB, but Windows tops out too.

There may also be a boost due to a larger cache size and possibly the front-side bus.

Ross

Yes. All NT based Windows versions have always been multi processor aware, and dual/quad core is simply multiple processors on a chip as far as the OS is concerned. As far as fully harnessing the power of such a setup, thats still mostly up to the programs themselves. The OS can multithread all the APIs below the program as much as possible to improve things, but that only goes so far.

I get a ton of use out of having dual core on my Mac, and am looking forward to my next upgrade bringing quad core as a minimum. Gaming is definitely taking advantage of multicore now, thanks to the consoles and desktop PCs both forcing the issue at the same time. It's also useful for running high quality VOIP calls while playing without either impacting either process.

Don't forget HD Freesat later this year as well.

I'd say it's further off than that, I doubt you'll see HD until after DSO, which could mean 2012 in some areas. HD on freesat is a much better possibility, certainly, it's the only reason why I'd put a dish on my house.

Any good pointers for info? With my 3-foot dish, I should be able to receive it over here...

http://www.freesat.co.uk/home.php

I don't think you need anything special for it, just a standard HD sat decoder I think. Some of the channels are already on FTA anyway, not sure about the HD ones though (not that there are many of them anyway).

Is this helpful to you then Julf?

http://hdtv4all.com/hdtv%20satelliet%20kanalen.htm

Well, looks like I just need to aim for Astra 2 and get a HD decoder then... Thanks!

Freesat is apparently headed for launch in May, although Channel 4 is tied into an encryption contract which lasts until October.

The rumoured pricing posted on Digitalspy is:

Freesat non-HD (box only) £35 excluding dish.
Freesat HD (box only) £99 excluding dish.
Freesat HD PVR (box only) £149 excluding dish.