posted by westfale on december 24th , 2004
INTRODUCTION
X86 ?
HOW MUCH SHOULD YOU PAY ?
IS OVERCLOCKING WORTH IT/SAFE ?
THE MANUFACTURERS
AMD
Intel
Transmeta
Via
INTRODUCTION
let's start by talking about what a CPU is and why it is important . the CPU is the brain of your computer (or your playstation , gamecube , palm handheld , etc) . it processes the vital data , and it can be told to do different types of work . you can tell it to help you make spreadsheets , or to play games ; or you can tell it to run a simulation of a thermonuclear explosion . over the last few years , a lot of this work has been off-loaded to the graphics chip for instance (see our VGA Guide) , or to dedicated sound processors . however , in the same time frame , games have become more complex and now feature more detailed physics models and better artificial intelligence systems . thus , the CPU remains a vital part of your system , and it's performance has a huge impact on the overall speed of your system . other factors (amount and speed of memory , graphics card , and so on) are also important , of course ; but the CPU remains perhaps the single most determining factor when it comes to overall performance of a PC .
X86 ?
"X86" is what PC processors (CPU = central processing unit , processor in short) are usually referred to . intel calls them IA-32 (intel architecture 32 bits) , and AMD calls theirs AMD64 (X86 with 64-bit extensions) . intel also has EMT64 (their version of AMD64) , and i'm sure some companies marketing department will come up with some more weird acronyms really soon :) . for a CPU to run windows XP and normal PC-type applications , it must be compatible with the X86 instruction set . there are other instruction sets out there : IBM and motorola use the powerPC IS (also used in sony's playstation 3) , the dreamcast console used a RISC processor from hitachi , sun uses SPARC processors , SGI uses its own brand of MIPS based designs .... i could go on .... PCs though use the X86 IS . period . there are machines that can run X86 code by emulating it : the mnacintosh has an application called "virtual PC" that allows users to run PC programs on their mac (the mac uses powerPC chips) , and intel's itanium processor can also run X86 code through emulation (the itanium uses what intel calls "IA-64" , which is NOT compatibel with AMD64 or X86) .
HOW MUCH SHOULD YOU PAY ?
at any given time , each manufacturer has several models of chip on the market . the fastest one usually costs a lot more money than the next model down . so unless you are a millionaire (and if you are , send me your money lol) , it makes sense NOT to buy the fastest model out there , and to buy the second or third fastest one instead . you'lll save a lot of money , and performance won't suffer a lot (the difference between a 3.4GHz and a 3.6GHz pentium 4 is negligible , all other things in the system being the same) . with the money you save , you can then buy more memory or a better graphics card (or whatever comes into your mind) . a system with 512MB RAM and a 3.4GHz chip will perform better than a system with only 256MB RAM but a 3.6GHz processor .
IS OVERCLOCKING WORTH IT/SAFE ?
to overclock means to make your CPU run faster than its official rated speed . you needa good quality motherboard to do this , and it will void your warranty . you can also break your CPU while overclocking , and good cooling (like an all-copper air cooler or a watercooler) is a must . to answer the question above : it is worth it and safe to those who know what to look for in a CPU , a motherboard , and a cooler . certain modles of chips are better suited to being overclocked , and an overclocker will often spend a lot of money on a good quality motherboard (reliable and with lots of adjustment options in the BIOS) . good cooling , as i said , is a must . i won't go into the details of overclocking here (that's an article in itself) , but if you know what you are doing and how to do it , you can save a lot of money and greatly increase the performance of your system . for more info on this subject , visit overclocker's club . please note that we are not affiliated with overclocker's club .
THE MANUFACTURERS
K8 : the K8 is replacing the K7 core . and it cannot be used in the same motherboards as the K7 . it is sold as "Athlon64" , "Athlon64 FX" , and "Opteron" . the K8 core is essentially a heavily revised K7 featuring 64-bit extensions , support for SSE2 (SSE3 will follow in later revisions) , and on-die memory and hypertransport controllers . the memory controller cuts RAM latency by about 40% , while the hypertransport bus (3.2GB/sec) takes the place of the traditional front side bus . for socket 754 athlons , bandwidth is thus 6.4Gb/sec (3.2GB from the RAM controller and 3.2GB from the hypertransport) , while the dual channel socket 939 CPUs have two onboard RAM controllers and a faster (4GB/sec) hypertransport bus (3.2GB+3.2GB+4GB=10.4GB/sec) . opterons (which come in the socket 940) have dual RAM controllers, but use the 3.2GB/sec hypertransport bus . 100 series opterons are single processor only, while 200 and 800 series are used for dual and 8-way multiprocessing , respectively (thus a model 146 opteron is just as fast as an 846 , but the 846 features extra hypertransport links which allow it to talk to other processors) . the K8 is supported by a large selection of motherboard chipsets , nvidia's nforce and via's K8T series are the most widely used (and for good reason , since they offer stability , performance and lots of features) . AMD will phase out the socket 754 during 2005 , so if you are interested in buying an athlon64 , i highly recommend getting a socket 939 motherboard/CPU . for multiprocessing , an opteron system makes more sense than an intel xeon setup (when you add a second opteron to your system , you also add more memory channels , while the xeons have to share the channels the motherboard provides) . socket 754/939 CPUs come with either 512kB or 1MB of cache , while S940 CPUs always have 1MB . the AMD chips are usually faster in gaming benchmarks than their intel counterparts , but the intel systems are faster running certain non-gaming applications . NOTE : there is one model of Sempron available on the socket 939 platform , this is based on the K8 core also but features only 256kB of level1 cache and is NOT compatible with AMD's 64-bit instructions . in my opinion it's not really worth buying , given that a "real" athlon64 (the 2800+) costs just 5 bucks more .
intel currently has two cores in its lineup , the older northwood and the newer prescott .Northwood : the northwood core is made on intel's 130nm process , and it is being used for both the company's high-end CPU (the pentium 4) , as well as for the budget chip (celeron) . it is being phased out and replaced by the newer prescott chip . northwood is available for the socket 478 platform and has a pretty good reputation among overclockers (especially the 2.4GHz part) . it features support for SSE2 instructions and has either 512kB (P4) or 128kB (celeron) of L2 cache . while all NW's feature intel's hyperthreading technology (which allows a CPU to use its resources more efficiently when dealing with multiple program threads) , this is only active in the P4 . the NW-based P4 is a very good performer , but the celeron just flat out sucks . the deep pipeline of the NW architecture combined with a lack of cache and a slow system bus means that the chip is often outperformed by budget AMD chips that run 800 to 1000 MHz slower . here's a comparison test at ananadtech , pitting a 1.6GHz AMD Duron (the Sempron's predecessor) and a 1.8GHz pentium 4 against a 2.6GHz celeron . to say that the cellie got its ass kicked is an understatement .
all in all the socket 478 is a very stable and mature platform , and certainly no bad investment (as long as you keep your hands off that celeron) , but feature wise S478 motherboards are being overtaken by their newer S775 brethren . so in the long run , the S775 will serve you better .
Prescott : prescott is the followup to northwood , and features several enhancements , as well as a few drawbacks . its pipeline is even deeper than the NW's (allowing for highre speeds) , but intel tries to make up for that by including even more cache (1MB on all pentium 4s based on the prescott core) . prescott supports the new SSE3 instructions (SSE speeds up certain multimedia tasks) , and comes in the new LGA 775 package . the prescott-based celerons are only available in the socket 478 format right now , but they are FAR superior to their NW forebears . they have both more cache (256kB , same as first-gen willamette-based P4's) , and a faster system bus (533MHz vs 400MHz) . they are still noticeably slower than a "real" P4 (and still lack hyperthreading) , but they are actually worth their money now . prescotts with 64-bit extensions should appear in stores early next year . the only real disadvantage of the prescott is the heat generated by the chip , which necessitates a robust cooler and a well ventilated case .
there are 3 intel X86 chips which i want to discuss quickly : the "Xeon" , which is the workstation version of the P4 (like an opteron is the workstation version of the athlon64) . xeons are pricy and if you don't need multiprocessor support they are NOT worth it . then there is the pentium 4 extreme edition : this is actually a xeon (with 2MB of additional level3 cache) , but in the socket 478/775 package . not worth the money , in my opinion ; paying $1000 to have a chip that is only slightly faster than a regular P4 is kinda dumb , especially since a 3.8GHz P4 actually outperforms a 3.2GHz "EE" and is cheaper to boot . finally , there is the pentium-M , a mobile chip based on P3 architecture but featuring enhancements from the P4 . this chip seems to perform very well , but is not yet widely available for the desktop . i will discuss it further when more desktop boards supporting it start to appear .
