AMD 64 versus P4 32 bit processor

[bim27142]

:roll:
what are the pros of having a 64 bit CPU when there is no official 64 bit OS yet out in the market and most programs still are on the 32 bit world? not considering the future, if we take our reference TODAY, what's the real advantage of having 64 bit processor? does it necessarily perform faster over 32 bit?

 

[TDiddy]

AMD 64 chip as a processor for a computer running in 32 bit is faster than p4 in about 95 % tasks

 

[suklee]

A64 32-bit > P4 32-bit

see above.

 

[bim27142]

why? has that got to do with the bandwidth or something? please enlighten me... i want to invest my money's worth...

like i know why dual channel is better than single channel because it doubles the bandwidth thus increasing memory performance... how about for 64 and 32 bit? what makes it faster in about 95% task?

inputs need not neccessarily be detailed, just to give me an idea...

thanks ya'll

 

[Priit]

AFAIK there's quite many linux distros compiled for A64 avalible. Only people who think OS=Windows are without 64 bits

 

[FullRoast]

bim27142 - It looks like your real question is something like, "Is the Athlon 64 better than the Intel Pentium 4?". As already been pointed out, its not really 64-bit verses 32-bit, although there a 64-bit Linux distro's now.

There is an old Anandtech article that describes the Athlon 64 architecture, but in very basic terms, the A64 architecture uses a shorter pipeline design that can execute more Instructions Per Clock, P4 uses a deeper (longer) pipeline with fewer Instructions Per Clock. A pipeline is string of hardware functions that execute parts of an instruction. In order for the instruction to be executed, it is run through the pipeline. See the article for more details.

For a given clockrate, say 2.4 GHz, the A64 runs more instructions (gets more stuff done) than a P4 running at 2.4 GHz.

It is hard to say that the A64 is better than th P4. A64 runs more IPC's, has better performance for most things, runs cooler than a comparable P4. P4 has hyperthreading (like having two logical processors) and is better at some application performance.

Hope that helps.

 

[Viditor]

Originally posted by: bim27142
:roll:
what are the pros of having a 64 bit CPU when there is no official 64 bit OS yet out in the market and most programs still are on the 32 bit world? not considering the future, if we take our reference TODAY, what's the real advantage of having 64 bit processor? does it necessarily perform faster over 32 bit?

The advantage of the A64 TODAY has nothing to do with 64-bit...it's just a more efficient processor. The reasons for this are numerous.
1. On-die memory controller allows for much faster "turn-around" (latency) to the Ram
2. Shorter pipelines also alows for a "faster turn-around"
3. A64 uses a 64K L1 cache, P4 Prescott uses a 16K L1 cache

There are many other reasons, but they are quite complex. The P4 Prescott is still the champ at media encoding, though their lead has dwindled down to almost nothing lately.

 

[bim27142]

FullRoast:
that's a good explanation, not being biased there...i get your open minded point... another thing, why do AMD CPUs run mostly lower clock speeds and lower FSBs yet performs at par with intel's GHz plenty CPUs?

also, in CPU-Z software, what does FSB and BUS SPEED refer to? isn't not FSB(Front Side Bus) theBUS SPEED already? like 800Mhz for P4 with hyperthreading or 533Mhz for non-hyperthreading?

 

[FullRoast]

The details of processor design are fairly complicated, but there are tradeoffs between how fast I can run a clock versus how much I can do for each clock cycle. The AMD processors do more for each clock cycle, but the clock cannot be run as fast. Intel chose a design that lets the clock run faster, but does less. The public likes the idea of a faster clock, thinking faster must be better. That isn't necessarily true. AMD came up with their performance rating scheme (3500+, etc.) to try and counter the impression.

FSB is the frequency of the bus clock, like 200 MHz. Bus speed is the rate that data can acutally be transferred (sort of). WIth a P4, an FSB of 200 MHz and a bus speed of 800 mHz means that the bus is dual channel (two paths for data) and double clocked (data can be transferred on both the rising and falling clock edge). The key thing is that theclock is 200 Mhz and the design of the data bus allows it to transfer data at 4 times the clock rate.

 

[bim27142]

oh ok...im somewhat confused and mislead by intel's 533Mhz FSB of their CPUs when in fact that is BUS SPEED and that the real FSB is just about 133Mhz? did i get it right?

 

[PumpActionWalrus]

Yeah, they "quad-pump" the host speed, so 800=200 host, 533=133 host

 

[bim27142]

ok, great... now i'm starting to appreciate AMDs road to microprocessor technology... so much for intel...

 

[gururu]

both processors are good. reasons for buying either one are legit. you can compare a 2.4GHz athlon to a 2.4 GHz P4, but the reality of it is that the athlon will cost more. an athlonxp with a clock of ~2.4GHz is actually listed as athlon3200/3400+ and competes with P4s in 3.0GHz class. Athlons can do as much with a lower clock rate. it is just a difference in architecture. the athlon64 series IMO is awesome. BUT, I haven't seen the games or apps that seperate it from P4s or for that matter XPs.

 

[MDE]

You can't really go wrong with either. If possible try to test both out and see which you prefer.

 

[Mik3y]

the added benefit of the athlon 64 is the fact that it's 64-bit ready. it doesnt have any effect on how well it performs in the 32-bit environment. because of its architecture, hypertransport, and on-die memory controller, the athlon 64 gets its performance from those and is clearly superior to the P4 overall.

 

[Gothgar]

Originally posted by: Mik3y
the added benefit of the athlon 64 is the fact that it's 64-bit ready. it doesnt have any effect on how well it performs in the 32-bit environment. because of its architecture, hyperthreading, and on-die memory controller, the athlon 64 gets its performance from those and is clearly superior to the P4 overall.

werd

 

[Lithan]

You mean hypertransport.

Basically, A64 is a stronger processor in 32bit than a p4. 64bit may be gravy if you plan on using 64bit software before you uograde again. A64 is <=~ p4 cost, and in most instances is >= p4 performance.

 

[sbuckler]

Originally posted by: Mik3y
the added benefit of the athlon 64 is the fact that it's 64-bit ready. it doesnt have any effect on how well it performs in the 32-bit environment. because of its architecture, hyperthreading, and on-die memory controller, the athlon 64 gets its performance from those and is clearly superior to the P4 overall.

In the above quote hyperthreading is a P4 feature not A64. Quite how important it is depends on what you do - if you like doing more then one thing at a time, particularly where one of those things is very cpu intensive (e.g. programmers often compile in the background while working on their code) then hyperthreading is essential. In the "dual core" future if all the apps go multi-threaded to be able to make use of both the cpus then that would mean single cpu's with hyperthreading would be able to run these apps much better. However I wouldn't expect many heavly threaded apps before 2006.

As to whether you need 64 bit it depends really on how cheap memory gets. The biggest advantage of 64 bit is you can have more then 3 or 4 gig of memory. You can take advantage of some additional 64 bit cpu instructions for more performance, but then there are disadvantages - you have doubled the size of all your pointers meaning a 64 bit program will need more memory and have to move it around faster to do the same thing as an identical 32 bit one. There will also undoubtedly be some backwards compatibility problems for early implementers (i.e. existing 32 bit apps/games not working properly).

Having said all that if you mainly plan to play games the A64 is undoubtedly quite a bit faster. I would buy one for a games machine but make sure you get a 939 one which has dual channel memory. Contrary to some opinions A64's do need the extra bandwidth sometimes, particularly with the newest games and when the going gets tough (e.g. in latest A64 4000 reviews the CS:Source test shows a 1.8ghz 3000+ with dual channel beating a 2.4ghz 3400+ single channel).

 

[carlosd]

Originally posted by: sbuckler

Originally posted by: Mik3y
the added benefit of the athlon 64 is the fact that it's 64-bit ready. it doesnt have any effect on how well it performs in the 32-bit environment. because of its architecture, hyperthreading, and on-die memory controller, the athlon 64 gets its performance from those and is clearly superior to the P4 overall.

In the above quote hyperthreading is a P4 feature not A64.

I think he wanted to say Hypertransport.

 

[bim27142]

Originally posted by: MDE
You can't really go wrong with either. If possible try to test both out and see which you prefer.

these are great opinions, thanks guys! yeah, i agree, both of them make very good processesors... one maybe be good over the other one in specific apps but basically they both get the job done... for ordinary users like me, can't really tell the exact performance difference between the two... i'm just trying to be a cautious buyer and want to get my hard-earned money's worth just like everybody else i think...

 

[Mik3y]

Originally posted by: carlosd

Originally posted by: sbuckler

Originally posted by: Mik3y
the added benefit of the athlon 64 is the fact that it's 64-bit ready. it doesnt have any effect on how well it performs in the 32-bit environment. because of its architecture, hyperthreading, and on-die memory controller, the athlon 64 gets its performance from those and is clearly superior to the P4 overall.

In the above quote hyperthreading is a P4 feature not A64.

I think he wanted to say Hypertransport.

woops. i meant hypertransport. sorry guys, i was typing this really fast like 2 minutes before i had to leave to class. my brain doesnt function well early in the morning without a cup of joe.

 

[bim27142]

is hypertransport comparable to hyperthreading?

 

[Markfw]

Originally posted by: bim27142

Originally posted by: MDE
You can't really go wrong with either. If possible try to test both out and see which you prefer.

these are great opinions, thanks guys! yeah, i agree, both of them make very good processesors... one maybe be good over the other one in specific apps but basically they both get the job done... for ordinary users like me, can't really tell the exact performance difference between the two... i'm just trying to be a cautious buyer and want to get my hard-earned money's worth just like everybody else i think...

I agree. One thing to think about, is if they are equal at encoding on average, what is the upgradability ? Intel has killed any updates to socket 478, which leaves the 775 hot-socket preshot , and I wouldn;t go there. Plus they are much more exspensive. With socket 939, you have a future, and they are cheaper, and you have any possible advantages of 64-bit when it comes to fruition.

 

[Vee]

Originally posted by: bim27142
is hypertransport comparable to hyperthreading?

No, they are two completely different things.

Hyperthreading means the P4 has thread awareness inside the core, and can keep the flow of two simultanous threads seperated. This means it looks like it is two CPUs, from the OS sheduler. It still can only run one thread at the time, but since the P4's execution units are waiting so much, because the branchprediction has hiccuped or something, why not run the other thread awhile, while we're waiting?
So actually, total sum of performance increase. Provided we get two threads from the sheduler, of course.
The reason ht works so well on the P4 is actually due to that it is an inefficient processor. For the opposite reason we will probably not see any hyperthreading on AMD's cores, or Intel's new P-M derivative cores.

People who can't be bothered to manipulate Windows process priorities, also much appreciate that hyperthreading, in some cases improve responsiveness during heavy multitasking. Due to the aforementioned fact that the sheduler sends two threads to the CPU.

Hypertransport OTOH, is a link replacement for all old databuses. Like the FSB.

 

[Vee]

Originally posted by: bim27142
oh ok...im somewhat confused and mislead by intel's 533Mhz FSB of their CPUs when in fact that is BUS SPEED and that the real FSB is just about 133Mhz? did i get it right?

Huhm... 533FSB is the theoretical maximum speed of transfers. 133MHz is the bus CLOCK, just the clock, that syncs the transfers. Clocks are just clocks. It doesn't do any work. It's important to get them right, but there's not much reasons to be terribly impressed by high clockspeeds.

But Bandwidth is a minor part of system performance from memory. More important is latency! That's why old systems with old sdram 133 do as well as they do, and why the new DDR2 standard fails so miserably, despite high theoretical bandwidths.

The FSB connects the CPU with the 'Northbridge'. The Northbridge then connects to the memory by the memorybus, which does not need to run on the same speed as the FSB. The Northbridge also connects to AGP-port, PCI, Southbridge, IDE-channels,.. Basically the Northbridge is the crossroad, and only one road leads to the CPU, the FSB.

Edit: And the A64 doesn't have any real FSB. It connects directly to RAM with its own memory controller, and to Northbridge and then everything else with hypertransport.