Rage3D Review: Phenom II - The Road From K8 to Deneb

[Lupine]

AlexV has written an article covering all that is Phenom II for your ocular enjoyment. Dig in!

Rage3D takes a lucid look at AMD's new CPU, the Phenom II (codename Deneb). Along the way we'll follow the twisty route AMD took from K8 to Deneb and, perhaps if we're lucky, learn a thing or two about what makes a processor a Phenom.

Phenom II - The Road From K8 to Deneb

[Pongo]

Thanks for such an informative piece. I will have to reread again there so much there to have sink in.

I really hope AMD can diversify itself enough with Deneb to stay competitive until Bulldozer. Is there any way they could change any of the mircoarch in a new stepping or is that beyond possible?

[seeker010]

Originally Posted by Pongo

Thanks for such an informative piece. I will have to reread again there so much there to have sink in.

I really hope AMD can diversify itself enough with Deneb to stay competitive until Bulldozer. Is there any way they could change any of the mircoarch in a new stepping or is that beyond possible?

they can tweak some of the instruction latencies and introduce new features and instructions, but that's about it. any significant changes requires reworking the core.

[Qualitier]

I've read more or less (I don't remember it quite well and I'm not expert enough) that the L3 cache solves a lot of speed problems of the current AMD arch, although the L3 isn't that fast itself, because it confines a lot of memory traffic inside the chip (otherwise iirc, main memory must be accessed for some coherency issues, by design).

According to other one of my reads, some inner narrow bus (L1 <-> L2?) hinders performance quite a bit. My guess is that this limitation is to workaround a physically weak design (known problems of AMD with some 65nm processes).

But, even if addressing any or both of these problems wouldn't increase performance that much (what's not true: 45nm "reformed K8" chips with L3 cache are close to Core2's in stock frequency, clock for clock performance and overclockability), it wouldn't be a big problem in itself. Not being able to reach the top Intel offers isn't either. Provided they can reach appealing performance points at good prices.

My Athlon X2! Brisbane!! 65nm!!! 512KB L2 per core!!!! performs about 30% less only than the Intel i7 920 in single threaded apps (notice that I'm comparing two chips from different ages). But it loses very clearly in overclockability and multitasking. Afaik the latter feature is where the i7 really shines respect to anything AMD has now.

I don't agree any statement about AMD needing "desperately" a complete architecture redesign. The current K8 products are appealing and very valid. Of course, any improvement is welcome, but that's about the future.

[seeker010]

well of course a large l3 cache helps with performance. if you have a 3 issue design having more data in cache means less stalled instructions. of course having a 99% efficient 3 issue design isn't going to cut it even against an 85% efficient 4 issue design.

[Wascrash]

I just read this. Good and thorough review. I ve always been an AMD fan since the mid 90's. I have to admit i have some intel Core 2 PC's now but really the AMD chips do what i need pretty dam fast. You cant beat the performance you get from them at the price you pay. You can build a whole system thats dam fast on the cheap. Im Typing this on a core 2 Desktop as of now and it is my main gaming machine but im getting the urge to go back AMD. I think it will serve me just as well and i dont count my fps in games as long as its smooth in game. That way i have an excuse to make this pc a folding machine lol.