Techpowerup found a post over at InvestorsHub which claims AMD's 65nm production process is having power leakage problems.
Here's the full post:
Interesting AMD 65nm Process Variation Analysis. I was looking through AMD's thermal
design guide, and found some interesting results. If you look at the IDD
current of their C1 states, you get an idea of the leakage at various voltages.
I looked at their current CZ (F3 stepping, 90nm) and their DD (G0 stepping,
65nm) parts at the max P-state (1.2-1.3V for 65W TDP parts and 1.3-1.35V for 89W
TDP parts) and min P-state (1.1V for all products). I pay special attention to
their 3800+ part, which was their downbinned part for 90nm (therefore, highest
leakage), and their higher bin parts, which presumably require binning for low
leakage in order to fit in the power envelopes.
Note that with the new price cuts, AMD's new 90nm downbin is a 4200+ part, which
is not listed in this already outdated thermal guide. For 65nm, their downbinned
part was the 3600+ part. Today, it is 4000+. Note that you can see the part name
in the ID Tag.
It looks to me like AMD splits 65nm parts into three buckets: let's call them
low, medium, and high leakage.
1. The low leakage parts are used for the 4800+ and 5000+ products. They are
lower leakage than AMD's best 90nm parts. This is good news. They draw about 8%
less current at 1.1V, and about 23-28% less current at 1.35V.
2. The medium leakage parts are used for the 4000+ and 4400+ products. They are
somewhat as high in leakage than AMD's leakiest parts on 90nm, and definitely
leakier than their 90nm median parts. The 4000+ part, for example, draws more
current at 1.1V than AMD's downbinned 3800+ part on 90nm. At 1.325V, they are
drawing more current than AMD's high end 90nm parts at 1.35V. This is certainly
not good news, and suggest that the median of AMD's 65nm process leakage is
worse off than at 90nm.
3. The high leakage parts are downbinned to the 3600+ chip. Although this part
has been removed from the current lineup, it's not clear whether they are still
producing these and selling them as 4000+ parts, or whether their process has
improved. At any rate, these parts are insanely leaky. A 1.1V, they are drawing
almost 50% more current than AMD's worst 90nm part. And good thing AMD
restricted the voltage to 1.3V, because even at this voltage, the leakage towers
over the entire 90nm product line. I think these results are pretty interesting,
and may explain why AMD has not been able to ramp 65nm. The leakage is killing
them, and only their lowest leaking parts are able to hit 2.6GHz at 1.35V, and
still maintain a reasonable power envelope. Also, I found something interesting
in one of the other AMD datasheets I was looking at. Ever wonder why AMD's
Brisbane chips do so much better in idle power dissipation tests done by
reviews...? It's because they enabled a new mobile
sleep state on it.
Check out Table 64 on page 278. Previously, desktop chips supported no better
than C1 Halt state. Starting with G-step (Brisbane), they now support C3.
Interesting that AMD has needed to start enabling mobile sleep states on their
desktop parts. Intel's mobile parts support all the way down to C4E, while their
desktop parts only support C1E. C4E flushes the cache and goes to a lower
voltage than regular C4. C1E is also lower voltage than regular C1. Note that
Brisbane also supports C1E and can hit lower idle power in that state. AMD
doesn't state the voltage of that state, so I didn't bother listing it in the
above tables. At any rate, their C1 is still at 1.1V, which is nice, because it
lines up with current 90nm parts. Anyway, I thought people would find this