I was really trying not to post the above question, but after a few days on the net, I am simply too confused, so before I crash out...

In the process of bying a new pc, I have settled on an AM3 mobo (ASUS - M4A87TD/USB3), but now need to narrow my CPU choice down - a lot!

PC is going to be used for: Development, VirtualBox machines, trading, internet and mail, etc. No gaming.

1. Should I go for Quad or simply a dual core CPU?

2. Having chosen the above, a Phenom II (with L3 cache), or will an Athlon II do nicely for me?


I am not looking for a cutting edge set-up, just something that will run smoothly and let me swap comfortably between my different tasks (incl. virtual machines, though max. one VM alongside my main OS at any giving time).
With this in mind, obviously it wouldn't do to pay 2-3 times up for a few percent improvement over the second-best choice (if that's what it comes down to). On the other hand, I do not fancy having to upgrade again in just a year or two.


I know that there is no catch-all answer to the above, but worse, searching the net for days, I can basically find any answer I want.
If some kind soul could guide me just a little, it would really be helpful, as I am losing my way a bit here.

(I know RAM is important too, but I will tackle that when I have the CPU nailed down.)

I am on PCLOS 2010, kernel 2.6.33.5-bfs.

Cheers!
CJ

Standard logic would say phenom 4 core is the better cpu. Load balancing is poor when there's only 2 cores, but power consumption must be higher if you're working 4. Then if power conscious acpi switches a few off, you take a while to wind up to max cpu power.

The day has gone, however when you need the best cpu money can buy; performance is often equally limited by more mundane things - video, chipset, disks, ram speed. I would also like L1 cache, or a good deal of L2. Is L3 1/3rd speed or 1/4 speed? It's probably slower - that's my point.

I would say that it depends on the uses that computer will be put to. I use my quad (Phenom 955) whenever I'm doing media processing or multithreaded programming. That's where they make a difference. For all other uses I turn to one of the single or dual core systems as the quad would be a waste of power for little if any extra performance.

If you are a regular user, you may actually do yourself a service by saving on the CPU and getting an SSD drive.

Oh wait, one thing I should add. The Gigabyte board I use with the quad has recently had a BIOS update which can disable up to three of the four cores. That would also save some power. I can't tell whether the feature is any good, though. I believe it is mainly intended for dual or triple core users who are experimenting with unlocking hidden cores.

I hear you, and this was along my line of thinking already.

I remember reading that the L3 was indeed a bit on the slow side; worse, it seems that, for the Phenoms I was reading about, one L3 was shared between the cores, thus actually slowing things down (by having to swap a lot).

Understood. As per my initial post, no multimedia - or at least, very little - on this PC.

My main concern is to be able to comfortably (!) work on/switching between several things at the same time. It could be:
a. Programming in a virtual machine, while keeping an eye on mail and eBay, or
b. Trading on one screen (I have two screens) while surfing the net on the other, maybe writing a document or two, or... well, you get the point.

Ok, I shall have to give this some serious thought. Thanks for the tip!

What I am getting from this is that - since Quad might be overkill for me - I would basically just be burning the extra oil for no reason, with added issues with heat.


Ok, the conclusion seems to be that a Dual core should be ample for my needs. What I am still fuzzy about, alas, it whether to just settle for the cheaper Athlon II or to cash out for the Phenom II - although it seems that the Phenom really does not add too much new to the scene after all...

So... Dual core Athlon II? Is it good enough, am I drawing the right conclusions?

Cheers!
CJ

a. I can do that fine on my four or five year old Core 2 Duo 6600. In fact, virtual machines benefit more from added RAM and faster drives than from a faster CPU. Of course, you need to make sure that the CPU has virtualization support (AMD-V) but that should be a standard feature of about any recent AMD CPU (unlike quite a few Intel CPUS).
b. That would depend more on your video card.

The Phenom II X2 series is actually quite a bit faster than Athlon X2 but then the question is whether you need it. For most of the things I am doing, I cannot tell any difference between the C2D I have referred to already and the fairly recent Phenom X2 550, which should be up to 50% faster according to benchmarks - but then that difference is not noticeable until I really start stressing the CPU (like compiling large pieces of source code, zipping big or many files or de/encoding videos).

The one I have...

I have an AMD 7750 Dual-Core CPU that has two speed steps, 2700 and 1350 MHz. Since it is governed, and throttles back and forth according to any momentary load, it naturally runs for the most part on one core at 1350 MHz.

Tux has wings; he must be a mighty flyer.

FWIW, my laptop has twin core turion 2 Ghz(amd cheapskate low power version). A ful kernel compiles in 13 minutes, and doing similar things I haven't been able to seriously work it. Dodgy ati video drivers did best at that - I got some combo that proved to be bits from one driver, and bits from another :-/. It is funny to see a cpu working at 150%, that's all.

I get you, though it wasn't so much the specific use and choice of apps, I was more after a general 'feel' - in lack of a better word - of how comfortably I could multitask between my daily chores (and fiddlings).
Your point about the -V support is a good one, I didn't even think of that. Please forgive my naivity on this - does that involve running (for instance) the main OS on one core and a VM on another? Or does the use of cores depend more on the apps than on the 'isolated' OS (eg. VM and main OS)?

I do do some rare video work, nothing professional and nothing to warrant a high-end expenditure, but to be honest, I just want what's best (for me)... I shall pay what it cost, I am just trying to avoid falling onto a ride in the newest, flashiest must-have vehicle, and fork out excessively on something that is a waste on me anyhow.
Also, as I mentioned, it would be nice if I didn't have to upgrade in a year or two (or next time the KDE people decide to emulate Vista, ha).

So... what you are saying is, if I were to buy a Quad, but don't need it, most of the power would be staying on the bench anyhow? Is that correctly understood?

Well, at least that makes you think you are getting something out of it, right?


You know what... I think I have utterly misunderstood the whole concept of multiple cores... Is it really this simple: If you have a 2ghz quad core, the max. speed would simply be 4 x 2 = 8ghz (discounting load balancing and other costs)? (Max = unlikely event that all four cores a being used optimally.)

I am currently using an Athlon XP 2600 (OC'ed some) and seeing the newer chips rated at, for instance, 2.5 ghz makes me think 'wow, is that all - no must of a gain in the years I have had my 2600'. Now, I know that this must simply be wrong, I am just not sure why...

Let me try to ask a concise question (if that is possible with my limited knowledge):
My current XP 2600+ have been adequate for my needs up and until the KDE 4 issue. Now it's a bit sluggish. In order to improve noticeably on this - say, double up or so, with my use as per all the above - what is the right buy?

Right now, from all your helpful answers, the right answer seems to be a dual core Phenom II.

Or even more concise; which of the below would be the better choice for my circumstances:
1. Athlon II X2 260 AM3 3.2Ghz 2Mb 65W (Euro 82.99), or
2. Phenom II X2 550 HDX550WFGMBOX 3100Mhz 1MB 85w (Euro 88.99), or
3. Phenom II X4 965 Black Edition Quad Core AM3 3.4 Ghz 8MB 125w (Euro 199.99). (note: I don't mind the higher cost, but only if I need it.)

I just noticed something weird: With my preferred dealers, most of the Athlon IIs are in stock, but all (!) the Phenom IIs are not available (except one black edition). What's going on, are the being phased out for some reason?

Cheers... and I do appreciated you helping me out here. I know my lack of knowledge in this field and naive questions must be a bit of a pain, so thank you all!
CJ

And with the motherboard that you have chosen, there is the chance to 'core unlock' an X II to an X III or X IV. This may or may not work and it almost certainly would limit your overclocking options, but overclocking is unlikely to be your focus.

The L3 cache means that the Phenom IIs are faster than the Athlon IIs at the same clock speed and core count. Option 2 is hardly any more expensive than Option 1, so I would definitely prefer that out of those two. Potentially, you could even underclock opt2, if it is too fast (I don't understand the phrase 'too fast'; maybe I meant 'consumes too much power'?).

Opt 3 is over double the cost of Opt 2, and, if you were lucky enough to get a 'core unlockable' sample, not much faster, so I'd still be going for Opt 2.

AMD seem to be continually having 'minor speed bump (+100 MHz clock speed) for the same or very similar price' kind of progress as they improve their process, and part numbers do not seem to have an extended life as this happens. Additionally, initially when yields were low and overclocking/unlocking on parts that only just passed their test parameters was unlikely to achieve night and day results they were more willing to give free rein to overclockers, knowing that they wouldn't get much out of it...now, with improved processes, there would be very easy gains to be had, thus cannibalising the market for their own, higher end, higher margin, parts.

The PII XII 555BE had also had good reviews, even if you don't overclock it and was only trivially more expensive than the non BE part (and has the core unlocking possibility...even if it doesn't unlock, it is decent value, if it does unlock, its a brilliant bargain).

BTW, the first rule, if you want performance (and maybe the first rule in every case) is have enough RAM; do not spend so much on the processor that you buy less RAM than you actually need.

Secondly, think about the processor heatsink/fan. I haven't recent experience with AMD fans, but the noise they used to make was a bit 'raw'; a cheap (but decent) third-party offering can be much better, particularly if you can operate it a low rotational speed.

I know what you mean, but:

• The biggest issue that I have is when it starts swapping (or runs nepomuk)...I should have more ram
• Any of the options are going to be faster than what you are used to
• If KDE 4 is the biggest issue, have you considered using something other than KDE 4? (I have, but I keep coming back, increasingly unwillingly)

I recently upgraded my Athlon 2700 system (somewhat OC'ed) to a quad core Phenom-II 955 system. My reasons were similar to yours; the Athlon system served me well for about 7 years but was now too slow and I run lots of virtual machines. I also watch movies on the computer and later generation higher definition movies just didn't play well unless I shut down LOTS of things on the system.

I went through a logic chain somewhat similar to yours, in that I didn't need to be cutting edge, but I wanted to build a platform that would last for a decade with relatively minor updates and I was not concerned about cost.

I decided to pass on SSD for now; write cycles are still limited and I didn't want something that would have a fairly hard end-of-life, particularly given the cost. I use SCSI drives, though I'm now exploring a gradual transition to SAS.

If your usage only involves one core, someone (either the kernel, or the processor firmware...I'm not sure who does it) will cycle among the cores in order to handle thermal management issues by distributing the heat. Your VMs will be told how many cores they have available as part of your VM configuration, but those cores are virtual cores; physical assignment is handled again by the kernel or the firmware, and it WILL rotate through the cores for heat management.

More cores does not give you a "faster" computer; each core can only run at a rate dependent upon its clock speed. However, more cores DOES give you more capability for parallelism, which has the effect of causing much more rapid servicing of pending processes and therefore less latency for processes that need to be performed, if those processes are waiting on the processor. This very frequently results in the appearance of a faster computer.

You may say: "I have no need for the parallelism", but - particularly if you like to run VMs, I would say that you would be wrong.

I run a very heavy system. Lots of stuff (including a full-up KDE4/Compiz environment) and I'm usually pretty lazy about shutting things down that I'm not using at the moment (particularly firefox). I commonly run a Windows 7 virtual machine AND at least one (and often two) Windows 2000 VMs at the same time - and, often enough, I have all the VMs busy doing things. I have my system scattered across 5 SCSI hard drives, organized in an effort to minimize HD bottlenecks in an environment where anywhere from three to six operating systems are simultaneously running. I do a lot of multi-platform and cross-platform development, and it is not unknown for me to have large compiles underway in three OSs at the same time. With my quad core, I have not yet managed to consistently use up the entire system, though I have at times managed average processor loads (per core) of greater than 90%. Prior to my upgrade, I would routinely bring the system to its knees.

I have found the purchase of a quad core to be fully justified and, after the prices drop a bit, I might upgrade to a hex core. I also might just wait until the Phenom-II line is about to go out of production (or until the new processor family won't fit my mobo) and buy the then top-of-the-line processor that will fit my mobo, and consider it done.

Firstly, I really want to thank you both for taking the time and your in-dept answers! There is so much info in your replies that I shall not reply to each snippet, just trust me when I say that it has been read and taken in, and is much appreciated!

Correct.

Sound logic, it makes sense. So, of those three, no. 2 it is!

I have it covered. It will be a minimum of 4Gb DDR3, quite possibly 8Gb.

And thus we - both of us - come full circle as you just described my experience too!

* * * *

I have just come to the same conclusion; for now, the word is 'wait' on SSD.

I understand the concept, I think - it's not unlike the old multitasking of Windows versus that of Amiga (where it actually did take cycles from different chips)... or with the math processors of olden days... or even with contemporary graphic cards, of course.
What gets me, though - and again, it me that's in the wrong, I know - it seeing a quad with a speed of 'only' 2.6... and thinking, well, where is the improvement over my trusty 2600+ OCed? Well, it is in parallelism, but how much would it actually boost my set-up when doing simple task (eg. watching a movie, or coding)? Hence my naive thinking that, in an (non-existing) perfect world, 4 times as fast, minus overhead, swapping and allocating.

And here, I think, is the answer to the real question I just wasn't smart enough to formulate! I guess that pretty well covers it, really!

Add to that:
... well, there I have it.

* * * *

Based on all your help, I simply decided, f- it, I am going for a quad Phenom, but... again, my normal outlets only seem to have the very expensive, new Phenoms now... (but loads of Athlons). I need to contact them to see if it's just a temporary backlog or if something else is up.

I think that this must be my last question on the issue... it is crunch time, and a decision has to be made... now, if only dealer availability will improve so I actually have the choice, of course!

sooo... If I were to make a decision on what's available to me today, it would be between these two:
1. ATHLON II X4 635 2.9GHZ 2MB cache - AM3 (Eur 113.99)
2. PHENOM II X2 550 DUAL-CORE 3.1GHZ AM3 (Eur 103.90)

So - and no, you are not the only one that feels that I am going around in the same circles, sigh! - what is better: Quad Athlon or Dual Phenom?

Maybe I should just stick with my last choice, go for the Phenom Quad and simply find a dealer that has one... or look at eBay, of course.

Cheers!
CJ

AMD is not completely truthful...

Your AMD XP2600+ has a clock frequency of between 1917 and 2130 MHz depending on the model, on a Front Side Bus of either 266 or 333 MTz., doing all the work with one core. A modern dual-core CPU is not only faster; all the other specifications have changed along with the frequency and have been correspondingly improved.

It was such that for some things involving graphics, the limited memory of a graphics card demanded that some of the processing load be shared by the CPU. Memory is now cheap and that problem has gone away unless you do something like rendering.

I include a pin-up of my sexy CPU cooler. It exists to satisfy the overclocking urges of those so inclined, but will also cool very effectively at low RPMs and very quietly. Mine is an Alpine 64 PWM, the PWM making control easy for my motherboard, but there are other, hotter models available.

http://www.arctic-cooling.com/catalo...php?cPath=1_43

I have one of these too, and a good, quiet case fan.

http://www.arctic-cooling.com/catalo...ath=2_&mID=105

I would say Phenom II X6 1055T if you want to run GNOME Shell, Compiz, or MythTV.

The problem is that these days, MHz (or GHz) is not a very good method of comparing performance. If you take a chip and OC it, then yes, it is faster. But you can't say that Chip A @ 2.8 GHz is slower than Chip B @ 3.0 GHz. The clock speed tells you how fast it cycles, but not how much it can get done in each cycle.

For instance, if I take a Mustang and rev it to 5,000 RPM and compare it to say a Civic revving at 5,000 RPM. They are both running at the same "cycle" speed, but one of them is producing a whole lot more power

So don't get hung up on "it's not that many MHz faster than what I have now" because that doesn't mean it won't be a whole heck of a lot faster.