CPU Checklist?

ironclaw

Hi Folks,

Some of you may have seen my thread regarding an AMD nightmare, however, thats almost sorted. I'm failry techie but CPU's are not my strongest knowledge base. What is the checklist for buying a CPU? What do you have to match up?

I know your first port of call is AMD or Intel, then the FSB, what else?

If you buy a processor, which has the correct fsb is it gaureenteed to work? Or does the BIOS play a factor? I know cooling would be an issue but is there anything else that can effect the CPU?

As an example:

My laptop has a 1.6Ghz Intel Celeron M 370, could I put a Pentium M 765 in it? They both has a 400Mhz FSB then only difference is the speed and the cache size (1.6Ghz Vs 2.1ghz)

Many Thanks,

ironclaw.

Solitaire

The trick is to avoid mixing and matching different generations of hardware More specifically: stay away from ancient mobos, they'll cause all sorts of trouble!

For Intel:

Core2 is still the industry standard. They all use LGA775 (Socket T) just like many P4/PDs so pay attention to the chipset instead. Core2 usually need P3X chipset to run. Some old high-end and more recent budget P900s will work with 65nm C2Ds and maybe even C2Q occasionally with BIOS updates but won't take 45nm parts; avoid these chipsets if you can. All compatible chipsets take DDR2 except the enthusiast-grade X48, which uses DDR3.
- E1000/2000/5000/"new" 6000 (45nm) are FSB800 (200MHz bus speed). Any modern Core2 mobo will support that. Ironically (given their budget status) you usually need a big multiplier to get decent speeds off a 200MHz bus speed so these parts are often very easy to get big overclocks.
- E4000/7000 and Q6000 use FSB1066 (266MHz). Middle-of-the-road parts. Generally not so hot for OC for some reason but fair performers at stock. Weirdly this trend is reversed with quads - they seem to prefer starting off on FSB1066 regardless of multiplier when it comes to OC.
- E6000 (65nm), E8000 and all mainstream 45nm C2Q are FSB1333 (333MHz) parts. With the exception of those high-speed E8000s (higher-than-normal multipliers) they tend to be poor for OC as thier low multipliers mean that mobo stability acts as the performance ceiling. Did I say that older mobos can't support FSB1333? If you want one of these get a P35 minimum, if you want to OC them get a high-end P35/45 or even a X38/48 if you can find one cheap enough.
- Most Extreme Edition parts are FSB1600 (400MHz). Even many decent P35/45 mobos don't support FSB1600 without OC in the first place! But most EE parts have unlocked multipliers so the only real concern is that the mobo's CPU voltage regulators are up for the job In any case if you have an EE CPU money is probably no object anyway :P

Intel only licenses CrossFire so if you want SLI you're gonna have to take a walk on the wild side with a tetchier and hotter-running nVidia chipset. General rule: nForce400i compares to P900; avoid! nForce600i compares to P3X and nForce700i to the current P4X lineup. nForce 790i specifically is analogus to the premium X48 being DDR3-only, having FSB1600 support out-of-the-box and typically bearing the fanciest multi-card setups and the nastiest pricetags to go with them :rolleyes: And for some reason a lot of cheaper nVidia chipset variants lack dual-channel capability on the DDR2

And then there's Core-i7. They use the unique LGA1366 socket. Only chipset for it is X58. DDR3 only, CF on all models, some pricier ones add 3/4card and SLI support in to boot. No nVidia parts here (or in AM3 for that matter) Bear in mind that even the low-end i7-920 is as aggressive as an EE C2Q and has major power and cooling requirements especially under OC!

It goes without saying, but avoid Pentium 4, Pentium D and Atom like the plague

With AMD you have less to worry about from an FSB point of view (IIRC its 200MHz bus for the last few years) and more about sockets and HyperTransport (HT). Again, things become so much simpler if we don't touch old stuff like Socket A/754/939/940 with a bargepole. That only gives us AM2, AM2+ and AM3 to worry about.

Problem is that vendors and retailers are a pain and often fail to differentiate; I've seen good AM2+ boards sold as AM2; unfortunately I've seen some *cough*Komplett*cough* sell old AM2 boards as AM3! :eek:

I'm not going to go into old K8 Athlons much here as the new AM3 ones will totally replace them in the budget sector very soon (it can't be too soon IMHO); basically you have the single core Sempron and meatier Athlon64, and the dual-core AthlonX2. All of which are really only for low-power apps given all the good ones have a 45W TDP, max. There is still a lot of 65/90W stock out there though and they're not even good for low-power jobbies.
K10 Phenom is the tri- and quad-core 65nm CPUs with the quaint TDP figures and equally quaint performance; on average 10% off the C2Q they're also stinkers in the speed stakes. Avoid.
K10.5 is where the business is at; there are dual, tri- and quad-core Phenom 2s (P2) and only cheapie dual-core Athlon 2s (which lack many optimisations and the L3 cache). These not only shrink the performance gap (in many cases the L3 cache is suspected to give the added edge) but ramp up the speed to boot; they're comparable to Intel's Core2 range and are very well priced.

AM2 is only good for old Athlon X2s due to limited HT bandwidth. nVidia's nForce500 and 600a series fall in here. Note that nForce680a is a special case; Socket F was a proprietary dual-CPU platform (think of it as a prehistoric Skulltrail ). Avoid all these if you can.
AM2+ is much better all-round and you can drop almost any modern AMD CPU in there (although an old mobo will obviously need a BIOS update to talk to a P2, for example). They are specifically meant for Phenom and the two early-bird Phenom 2 models, but old AM2 Athlons and even AM3 CPUs wil work (albeit with DDR2 instead of DDR3). nForce700 is the way to go if you want SLI instead of CrossFire.
AM3 is the new socket that is pin-incompatible with the old CPUs and allows the shiny new CPUs (AM3 P2s and the new low-end Athlon2 or A2) to run at their best. It takes DDR3 instead of DDR2 (the speed limit depends on the CPU, as the memory controllers aren't on the mobo). nForce900a is nVidia's upcoming contribution to the argument and it ain't out just yet. Which sucks if you need SLI because you have to go back down to AM2 and nForce700a.

I'll do mobile platforms some other time, but for the most part swapping about CPUs in them can get you burned.

In some cases, literally.

Unregistered.

Somebody should sticky this.

cherryghost

Unregistered. wrote: »

Somebody should sticky this.

yes. very good read.

dak

I bought an MSI 945GCM478-L mbo to replace a failed E-machine one . It supports an FSB of 533/800mhz. I put it all togehter but it doesn't work . The chip is a P4 SL6pp . Is it compatible with this mbo ?

Solitaire

Nope - that CPU needs FSB400 (100MHz bus) to run. That mobo literally can't run slow enough

eshortie

impressive and informative solitaire, nice.

cherryghost

needs more cowbell

dak

Solitaire wrote: »

Nope - that CPU needs FSB400 (100MHz bus) to run. That mobo literally can't run slow enough

Thanks for your reply ! That confirmed my worries .. I live and learn. I shouldn't try and keep old technology going ! Ordered a Dell inspiron 545 intel® Core™ 2 Duo E7400 processor (2.8GHz, 1066MHz, 3MB cache) Which will keep me happy for a year or 2 !