Why is Core i7 920 better than Phenom 2 955

Core I7 architecture is different to Phenom II architecture,
The frecuency (clockspeed) is not the most important factor anymore... Some differences:

I7 has more L3 Cache,
HT technology (which allows it to become an "" 8-Cores-CPU """ ),
A better memory controller system (Tri-Channel and up to 2000Mhz vs. Dual-Channel and up to 1600Mhz... right?),

By the way, there`s not a huge difference... It deppends on the software you use, on High-Res gaming they run very similar... But I7 is better in many other things.

and it has a slightly higher IPC (instructions per clock)

I think it is mainly due to Intel's superior cache and prefetch design, and, given the core2 cores have higher IPC than K8's then all things now equal ... both now have an IMC ... then the i7 is slightly faster on most applications than K10.5.

i7 and K10.5 both have cores that are essentially based on their predecessors.

You don't throw away 10 years worth of effort sorting bugs out of a core unless the previous model was better ... its very hard to start from scratch.

That's why they threw the Pentium 4 away and reworked the Pentium 3 (mobile) to come up with core2. P3 had a higher IPC than P4 ... the pipes were a better design ... or could be improved moreso. The core2 cores are at the heart of the i7 ... some changes of course.

Sorry for the oversimplification ... very crude explanation.

In my opinion the Phenom II is still better value for money and fast enough for most. The Average user isn't going to really see a difference. Oh yeah Hyperthreading is a Gimmick, it still only has four processor cores.

I agree ... for the price it is hard to go past.

But it isn't a better CPU.

I'll agree since you can find Newegg combos and pick up a Phenom II 940, 4Gb (2x2) DDR2 1066, and a AM2+ motherboard for less than the I7 920 costs alone. Although AMD is going to be in trouble when the I5 is released.

phenom II is better value until the i7 price cuts come, and i5 will be just a bit cheaper than i7 is now so AMD doesn't really need to be worried.

I think Intel is making a mistake though by using larrabee as a GPU, if they used it as a CPU they would easily own the market but then I guess the EU would stomp down on them for taking out the competition.

thanks guys... So the i7 does better work per clockspeed but not better work per dollar?

Actually I'm gonna build a desktop in quarter three, so this helps me although i don't really understand what some of guys are saying. lol

My plan is:

MSI GD-70
Phenom II 955
2GB Corsair DDR3 1333 DHX
Corsair TX 650
2 X ATI Radeon 4770
Cooler Master CM 690

Are these things suitable?
And good value for money?

I just want to play games a lot because I have restrained my self from doing so for three or four years

While this is close, its a bit off. Core 2 is actually based off of the Pentium III Coppermine that was a desktop part. What happened was that during the Pentium 4 era is that Intel needed a good mobile offense against AMDs Athlon that was low power and decent performance.

What they did is they wrapped the Pentium III Coppermineinto a mobile package naming it the Pentium M.

What they saw (well the guys in Israel anyways) was that it would run better than a Pentium 4 and clock per clock it whomped it and Athlon like there was no tomorrow.

So they took what they learned from Pentium 4 (lets faces it, the P4s pipeline design was better since it gave the ability to clock higher than others it was just the rest of the arch that had leakage up the arse) and applied it to the Pentium M thus creating Core 2.

Core i7 is Core 2 with a lot of IPC enhancements, a IMC and QPI.



Its not HT. And it was a gimmick but SMT actually does give a nice performance boost. But yes the average user wont see any difference which is why a Pentium Dual Core E2200 is suffice for most average users.



Well that depends on the Core i5s performance. It may be something AMD might worry about.

And Larrabee is a bit different. The design of the processors for it re mainly for GPU applications. Of course they could be using their design based off of Terascale mixed with Core i7s SMT (I think its supposed to be 32 processors with 64 threads and each core is capable of so many shaders) which will be great since Terascale was completely modular.

That means they could have some of the processors be PPUs(Physic Processing Units) and link it with Havoks Physics engine since they now own havok.

And you are right. If they released a CPU like Terascale or Larrabee they would end up monopolizing the market and especially the server market. Terascale was shwon to be able to do the same job as 130 CPUs (it was only 80) and only used 62w @ full load @ 2.5GHz per core. And we all know Intel doesn't want that to happen or they will be broken up again which in the end is bad for us end users.




Well what do you plan on doing? For gaming thats a pretty decent rig right there although for me I would go with the HD4870 2GB but thats cuz I am crazy.

Also, do you know what OS you plan to use? If its XP 2GB of RAM is fine but if its Vista or even Windows 7 4GB+ is always better.

You can't compare Hyperthreading from the P4 era to now. If it made no difference, why does both performance and power consumption increase when it is enabled?

jimmy did you not restate what I said?

Where was I off?

@Psycho, show me some results with them all running at 1600mhz FSB/HT/QPI and 3.2ghz clock speed.

otherwise it will not be a fair test.

Helloworld_98....you really don't get the point, do you? Psycho showed you exactly that HT makes a difference. Look when HT is OFF and when is ON on the same processor and you can see the difference.

The fair test is the price test so you should compare 2 processors with the same or similar price.

^ Yes but he also uses that same graph in situations where my point has more meaning.

And the extra bandwidth gives HT it's performance boost, drop the QPI down to 1600mhz and in theory there will be less difference between the i7 with HT and the Phenom II.

Drop the clock speed and slow it down. No kidding?

Asus 790FX AM3 / PhII 720BE: $320
http://www.newegg.com/Product/ComboDealDetails.aspx?Ite...

Anandtech: Phenom II X3 720BE & CrossFire X Performance
http://www.anandtech.com/mb/showdoc.aspx?i=3533&p=9


Need OS and gaming resolution to tighten things up ...

I'm guessing this was aimed at me but until we fair out the playing field on the CPU's we won't actually know which one is faster clock for clock.

You want to compare apples with pears. You can't. The only thing that we care of is the performance. Real tests and the price that we are paying. It is the same thing when AMD had lower speed processor (Athlon 64) compare to Intel (Pentium 4 and D) but still were much better than Intel. In the end doesn't matter how big is the FSB, core speed, cache memory,etc. Is important how much processing power can provide.

^ well lowering the QPI multiplier would be a start.

How is it fair to slow it down? I don't see the logic. Unless you slow the HyperTransport bus speed as well, then it's fair, because both are being restricted. Restricting one and not the other is not fair. By similar logic you could say "let's disable some of i7's cores and then it will compete evenly with Phenom II"  

I agree with Random. Why would you lower the CPUs QPI and not the HTT? Do you not like seeing a lower speed CPU beat the pants off of a higher clocked CPU? It happens all the time (Athlon X2 vs Pentium D?)

Using your logic as well, we should lower Phenom and Phenom IIs HTT to match that of the FSB of a C2Q for a FAIR and EVEN comparison when looking at that.

And rey, you said it was mainly based off a mobile part. It wasn't. It was based off of the roots of the Pentium III (desktop). And the P4 had a much better pipeline arch it was just much longer. Intel took the pipeline abilities of P4, shortened the pipes and made a lot of enhancements to the IPC, cache and such based off of Pentium III.

Every process gen is in Core 2/Core i7 somehow. Just like I am sure every gen (K6/K6-II/K7/K8) is somewhere in Phenom II.

Actually i7 has less cache compared to Phenom II. Phenom uses exclusive cache, i7 are using inclusive cache. Inclusive cache duplicates data in different cache levels. Exclusive cache don't do that.

http://en.wikipedia.org/wiki/CPU_cache#Exclusive_versus...

Just stay away from them PCChips cache chips they used to put on the old 486's.

The legs weren't even connected ... now that's exclusive !!

hyperthreading is not a gimmick dork! Read up on hyperthreading before you call it a gimmick. Ok, let's make it fair, Hypertransport is a gimmick.

The problem with exclusive caches is that the hypertransport bandwidth has to be used for snooping in the other cores' caches. See HERE :

On the other hand, due to inclusive technique, Core i7 also has less cache miss than Phenom II (theoretically speaking). High rate of cache miss means in the case core cannot find the file in its L1 data, it will then seek data in L2, L2s in other cores, and L3s (also segmented among cores), before finally hitting the RAM. This causes outrageously high latencies.

Core i7 latency is waaay higher than PhII.

PhII's cache is slower than the Core series CPUs too.

Not really.

K10's latency:


Core i7's latency:


Not only that, the chance of Core i7 having a cache miss (which warrants a read from the RAM) is much lower than Phenom II due to inclusive cache.

^ +1. Also note that for Istanbul, AMD is including a snoop filter that will look in the other 5 cores' caches for data before heading out to main memory, in an attempt to catch up to Intel. Of course, this will consume some of the hypertransport bandwidth.

does that chart apply to the 955 too?

I don't see why not. The 955 is just a Phenom II 940 @ 3.2GHz. The actual chip itself is pretty much unchanged just mainly the clock speed.

Yeh, that and a higher HT speed.

hey tomshardware didn't notify me about the replies to this thread....

yes I only want to play a lot and lot of games and I will be using Vista then will change to windows 7. Am planning to use a 22 inch monitor.

Thanks for the answers. Really appreciate them.

22-inch very likely equals 1680 x 1050, right?  

2 x HD 4770s have looked really good at that rez - and I was surprised how well they have mostly performed at 19x12, too.

It's a tough call (but) if I were gonna spend $200 today I'd snag an HD 4890 1GB for $200 AR ---->>
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

And later on this year when you want to reward yourself (and the price continues to drop) I'd snag another one (so you can play all the upcoming games really fast on that new 50-inch 1080p plasma you get for the holidays - LOL)

blah, blah. tired of seeing these pics....

At least we have a browser cache. Imagine if you had to download them every time? I'd hit my bandwidth cap in a matter of days.

lmao, good one. Damn i understand being proud of my rig, and it does look nice, but why in every thread?

....so is that your computer?

I am not tired of seeing those pics.

Just stick another 4870 in the box soldier.

Nice to see your quoting Scotty W there Yo ... he writes superior articles.

Hes got speed stickers on the side panel helps overclock with the magic green AMD lighting meaning the overclocking gnomes are working hard.

Word, Playa.

Don't forget the Mac keyboard.

jealous poor peons without the cash to bling up your rig ... like me.

I have the cash, I prefer to keep it.

I still like how the "screenshots" were taken with a camera. Shows true class.

^+1 lmao

I am too embarrassed to put up a photo of my PC.

She is a bit fat and has stretch marks.

Is a real goer though ... only locks up very rarely.

I will love her to eventual bits.