CPU "IPC"??? Low end CPU's can't match high end CPU's at the same speed??

[Kunaak]

I have been trying to learn more about the "IPC" of CPU's.

this is only something I have read about here, and on some other forums, where people have stated.

that a low end CPU, say a XP 1700, has a lower "IPC", then say a XP 2100, so when the 1700 is at 2ghz, and the 2100 is at 2 ghz.
the 2100 will still be faster, cause it has a higher IPC rating the the lower end XP 1700....

atleast thats what I understand of this.

this next part is pure speculation, so please bear with me.

we all know the AMD's do 9 calcuations per cycle or something like that.
but say, the xp 1700 does 10 instructions per calculation, that would be 10x9=90.
then say 12 instructions per calculation, that would be 12x9=108.

thats just pure speculation for me personally to explain what the "IPC" may be, and how it may affect the CPU.

of course that part is simply speculation, cause I don't really know...
but it helps me understand, why people say, a lower end CPU will not beat a higher end CPU, even when at the same speed.

can anyone, shed some light on this?

I really want to learn about this in more detail.
just, after a few hours on the net, didn't really help to shed any light on the subject, and although I emaild AMD, they were of little help.

[felix88]

Insane Clown Posse??! :eek: :p

in all seriousness, an XP1700 at 2.0GHz will give nearly identical performance to an XP2100 at 2.0GHz.

2 chips from the same family will have similar performance when running at the same speeds, regardless of the original speed. keep in mind that an XP1700 and an XP2100 could very well come off of the same wafer, so they are identical internally.

[pulverizer]

^
yep, any chip with the same archetechture, will perform the same amount of Instructions Per Clock. This is why AMD uses the performance rating, because the Athlon performs more instructions per clock than the Pentium 4, which is why when an Athlon and a P4 are both at say 2.0GHz, the Athlon will kill the P4.

[freeloader]

When both CPU's are at 2ghz, they will both do the exact same amount of work; assuming the front side bus and CPU multiplier are identical.

The XP is rated at 9 IPC, regardless what it's actual clock speed is. A 1700+ has the same IPC as a 2100+. The 2100+ gets more work done simply because it operates at a faster speed, that is, it oscillates 1.73 billion times/second compared to 1.47 billion times/second for the 1700+.

In some circumstances, an overclocked 1700+ (to 2100 speed) can be faster then an actual 2100. Synthetic benchmarks (Sisoft Sandra) that purely measure CPU speed will be identical. Say you take a 1700 and overclock it in the following manner (11x158=1733 roughly), you've increased the FSB by 25Mhz! In games you might notice a 5 FPS increase over a stock 2100. I hope I haven't confused you further...