AMD's Phenom Unveiled: A Somber Farewell to K8
by Anand Lal Shimpi on November 19, 2007 1:25 AM EST- Posted in
- CPUs
Socket-AM2+, Not So Positive?
When AMD first started talking about Phenom it boasted backwards compatibility with current Socket-AM2 motherboards, as well as a new Socket-AM2+ platform that would enable higher performance and better power management.
We are currently looking into Socket-AM2 motherboard compatibility, but not all vendors have Phenom-ready code for their motherboards as of today. While Phenom should work in virtually all Socket-AM2 motherboards, it's tough to say which will work by the time you can actually buy these things.
AMD's Spider platform, well, minus the graphics card - the 8800 GTX is still our testbed GPU of choice.
Socket-AM2+ motherboards, most of which are based on AMD's new 790FX chipset, were supposed to bring a tangible performance increase when paired with a Phenom processor. Phenom's L3 cache and North Bridge work on the same power plane, one separate from the rest of the CPU. Socket-AM2+ enables the use of two separate voltages, one for the L3 cache/NB and one for the rest of the CPU, whereas Socket-AM2 motherboards run the entire chip at the same voltage. The original plan was for Socket-AM2+ motherboards to run the L3 cache/NB at a higher frequency than the rest of the chip, unfortunately it looks like AMD wasn't able to make that happen.
Socket-AM2+ in action
Currently, the L3 cache/NB on these chips runs at a fixed frequency that's actually lower than the rest of the CPU frequency: 2.0GHz. We tested Phenoms running from 2.2GHz all the way up to 2.6GHz, and in all cases the L3 cache and North Bridge ran at 2.0GHz. We're not sure if this will ever get fixed, but it's somewhat disappointing as it was supposed to be a major reason for upgrading to Socket-AM2+ (but it's good news for current AM2 owners).
Right now it looks like the only benefit to Socket-AM2+ is support for DDR2-1066, which we've been having problems with internally already. If you've got a good Socket-AM2 motherboard, you may not need to upgrade to get the most out of Phenom.
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ChronoReverse - Monday, November 19, 2007 - link
Yeah, I was in a similar position a couple months back too but I could tell from the winds that the Phenom wasn't going to be that much better than the Core2 if at all so I sprung for the Q6600. Looks like (unfortunately) my estimation was quite correct =/stmok - Monday, November 19, 2007 - link
...And I guess it looks like the wait wasn't worth it.This article confirms to me I should be leaning towards the Intel C2Q Q9450.
rhatsaruck - Monday, November 19, 2007 - link
On page 4 titled "Socket-AM2+, Not So Positive?" Anand writes:Currently, the L3 cache/NB on these chips runs at a fixed frequency that's actually lower than the rest of the CPU frequency: 2.0GHz. We tested Phenoms running from 2.2GHz all the way up to 2.6GHz, and in all cases the L3 cache and North Bridge ran at 2.0GHz.
What's the performance impact of this limitation? I don't know how to quantify it. It seems like it might have a material effect on performance. Perhaps Anand can re-run his benchmarks at 1.8 and 2.0 GHz to get a sense of the performance boost when this limitation doesn't exist. From this we might be able to determine how much this shortcoming effects performance at speeds greater than 2.0 GHz.
Iketh - Monday, November 19, 2007 - link
My Athlon 4200+ (2.2ghz) overclocks to 2.7ghz stable. Anything passed that and the second core skyrockets too high in temp and fails prime95 torture tests, while the first core has yet to fail ANY tests and runs up to 10 degrees C cooler.My point is the individual core overclocking is the only positive I see out of phenom. If i had this ability in my current athlon 4200+, it'd be clocked at 2.7 and 3.2+ easily.
Omega215D - Monday, November 19, 2007 - link
Ahh the old 9700 makes a comeback but too bad it falls a bit below expectations compared to the 9700 GPU by ATI who is now AMD.Maybe there's still time to make some tweaks to the processor?
GlassHouse69 - Monday, November 19, 2007 - link
well.too bad for amd. they are toast it seems.
if it managed to be as cool and quiet, then I would have gone there on a quad because of price plus they have better and more consistently cheap + featured motherboards.
sux.
Well, on that thought, the new 790x motherboards with this actually might be low power when its all set up and done. fx or x I think does relatively the same thing. isnt the chipset supposed to be incredibly low wattage?
johnsonx - Monday, November 19, 2007 - link
Everyone knows AMD processors have always been, and will always be, far superior to the crap from Intel. Any article suggesting otherwise is clear evidence of pro-Intel bias, that indeed you all get weekly checks from Intel for the favorable press. The reality is that most Intel processors really don't even work at all; all the supposed PC's sold with Intel processors secretly use AMD processors instead, but again Intel pays off the companies to say they're Intel Inside. Intel has an endless supply of money because of their unfair business practices and the Magic Money Fairy.JumpingJack - Monday, November 19, 2007 - link
This is outright kiddin' no one can be that stupid.Bonesdad - Monday, November 19, 2007 - link
is that you, Cramitpal???ESD4300 - Monday, November 19, 2007 - link
Lol. What a fucking clueless, moronic fanboy