So I'm doing a little research, to upgrade my old Pentium to a PIII or PIV or Athlon or whatever. From the descriptions, these chips are faster for two reasons:

1. Higher clock speed.
2. Improved architecture and extended instruction set.

I can see how the improved architecture can help things out, but what about the instruction set (MMX,SIMD, etc.)? It would seem to me that the MMX instructions, for instance, would certainly speed up things like graphic rendering and the like, but if the program doesn't use the instructions, they might as well not be there.

My copy of IE5, for instance, runs on the Pentium just like it does on my Pentium IV. Do they have conditional instructions so that they can take advantage of the enhanced instructions, or do they just go with the lowest common denominator?

So --- I'm trying to get past the hype. Why worry about some neat feature if you can't use it?

In the early 80's RISC architecture (reduced instruction set computer) was the rage. For any task there is an optimal number of instructions that would ensure that a certain task in with a gicen computational load (from other processes running in forground or background) is accomplished in the most efficient manner. Any more or fewer instructions would increase the time for completion. This is analogous to saying that there is an optimal number of roads in a network of roads that minimises the driving time from point A to point B in qa given set of traffic conditions. More or fewer roads will cause congestion. It is a complex OR problem.

If it was me I would buy an AMD64 so I was ready for 64 bit computing. AMD is cleaning up on Intel so far there. Not much s/w yet, but it's coming.

Things might be different in a year... or less... but right now, AMD is faster & cheaper... not just the CPU, but much faster access to memory & I/O.

I picked this up for $200 bucks last week after rebates. I figured I got plenty of speed per dollar. Your mileage may vary. ^

http://www.compusa.com/products/prod...ct_code=320322

I'm waiting until dual-cores are more readily available. That, plus dual video cards and a high-end audio card (like m-Audio) and I'm ready to start swearing at Longhorn. Sorry, Vista. Sorry, XP2.

MisterMossberg of www.wsj.com fame just reviewed two $600 machines today and gave both nice marks (.....We tested Hewlett-Packard's H-P Pavilion a1120n and the T6520 from eMachines, a much smaller discount PC maker that merged with Gateway last year.

Of course, other well-equipped computers may go on sale for close to $600 from time to time, but these models are stand-outs at their regular price. You could also spend much less and get an adequate PC for the most basic tasks. But you will forgo a lot of the power and features in the $600 models we tested....)

MisterNice

Thank you all, but my original qiestion (perhaps poorly worded) has more to do with the supposed advantages of the later processors.

For example, MMX technology has been available for about 10 years, and is included in all the Intel processors since then. I did some experimenting with it back then, but it all had to be done in assembly language. The results were pretty spectacular in the areas of video processing, etc. Sometimes a factor of 10:1 or more in performance.

However, if one doesn't use these instructions (and other later improvements), they might as well not be there. I'm presuming Microsoft and the other guys compile their code (C? C++?) and thus are dependent on the compiler to generate the proper instructions. And if they do, does the code notice that the processor has these neat instructions and use them, or do they just go for the fat part of the bell curve and get the stuff to market as quickly as possible?

Since the code seems to work properly on stuff as old as 486's, as well as a Pentium IV, I'm questioning whether I should worry about what "enhancements" a given chip has, since I might not ever use it anyhow.

My 2 cents:

There has been a real proliferation of acronyms like SSE and MMX for the CPUs and these days, you're likely to find a long string of those if you were to list every one that a modern chip is capable of.

But gone are the days of exclusive Intel/AMD-only proprietary instructions which rendered non-compatible systems and programs horribly slow, for 2 reasons:

1. The two companies now support pretty much every instruction sets, regardless of whose set
2. Most everyday applications don't reduce in speed drastically just because your chip doesn't support a very recent, particular set (for example, I think AMD only very recently added Intel's SSE3 support)

So, from my limited experience it's just best to ignore what instruction sets a chip has, and go for the right compromise in speed, characteristics and price. The current "thing" is Dual-Core and, if your budget allows, the AMD X2 series seems to be the best mid-range processors for most applications at the moment. Plenty of materials available on the net to reach a decision.

Since you are still using IE5 (YIKES!) on one PC, you must be using Windows.

MS is doing all their dev work now in C++ and increasingly C#, which both then use the Visual Studio compiler. So, if you are using Windows XP on a P4 or an AMD, it's not going to make any user-noticable difference at all. On Windows 32 bit platforms it's now all about PC subsystems and their respective cards and how their memory and drivers are optimized/tweaked.

If you move to a 64 bit capable processor, that's not legacy crippled with the Intel x86 architecture path, like the AMD 64, then you will start to see O/S software and application software start to take advantage of said 64 bit improvements and efficiencies. Will you notice? Who knows... it's not all there for yet.

And I read the WSJ this morning -- that eMachines is killer for 600 bucks: AMD 64 3400+,1GB RAM, 200GB drive, dual CD/DVD +/- RW burners, USB, firewire, card readers and MS Media Center O/S (no tuner card though).

I want one! ^

I think your best bet is to look into Motherboard/CPU combo's.
If your still using a regular pentium your best bet is just to upgrade.
I like the E-Machines that were mentioned above.
Since the day that old workhorse pentium came out, things have change as I'm sure your well aware. Why not just upgrade your sys?

Check out cheap processors at Newegg, along with an ECS or similarly inexpensive motherboard.


All the instruction sets are shared by Intel/AMD - I certainly wouldn't want them to be a factor in my decision.

Yes, I have an older eMachine laying around and it struck me as pretty good value for the money. 500 MHz Celeron or something like that. Since I don't waste a lot of time with mindless games or downloading porn and so on, it handles pretty much all of my computing needs fairly well. Unfortunately, it's going to my daughter and my PIV is going off somewhere else, so it's either back to the Pentium or bite the bullet. Nowadays, that bullet isn't very big.

Just to be clear, I wasn't thinking of only upgrading the cpu; I was looking for a whole system. Besides, you can't just plug a P IV in a Socket 7 machine.

Just one other thing to note, Dell will be running some really good deals in October because it is near the end of their quarter. Check out http://www.gotapex.com for deals.

Yes, the compiler creates multiple codepaths that check with the CPU to see which instructions it supports. If it supports SSE* instructions, the program should take the optimised codepath. One of AMD's allegations in their antitrust lawsuit against Intel is that Intel compilers are creating executables that will not use the optimised codepath on AMD machines, even if the CPU reports that it supports the instructions needed.

That said, I wouldn't worry about which instruction sets your CPU supports, as Intel and AMD tend to cross license all that stuff anyway. The sweet spot in price/performance right now appears to be AMD's 64 bit chips. The 64 bit ones are nice because they run existing 32 bit apps natively, and their extra registers mean they tend to run 32 bit apps even faster than the 32 bit chips. Dual cores are nice, but are still too expensive.

I can understand why you're confused, because most of the replies to your technical questions have been misleading or flat out wrong.