5 GHZ+ Phenom II Overclock on LN2
Subject: Processors | November 20, 2008 - 03:10 PM | Josh Walrath
Today AMD was showing off its upcoming desktop Phenom II processor to a handful of journalists, and one of the main topics of the presentation is the "headroom" that AMD is building into the Phenom II processor.
The die shot of the 45 nm Phenom II. 2 MB of L2 (512 KB per core) and 6 MB of L3 shared makes this an interesting part from the CPU underdog. Throw in some serious refinements to the underlying Phenom architecture, and suddenly AMD has a chip that can much more adequately compete with what Intel has out there currently (and upcoming).
As we all know, the Phenom II will be AMD's second 45 nm part (the first is officially the Shanghai server part) that is scheduled to hit Q1 09. This heavily redesigned processor based on the Phenom architecture has already showed some significant per clock performance gains over the older Barcelona product, and AMD considers this to be their best design ever in terms of performance, functionality, and eventual clockspeed. The first desktop products are expected to hit 3 GHz at the top end, but AMD has been hinting that the Phenom IIs can do a lot more in the hands of an enthusiast.
The first leaks were that the Phenom II could hit 4 GHz on air cooling alone, though we obviously wonder how extreme that air cooling is. Well today AMD had some actual demonstrations at their gathering, and the Phenom II was able to hit 5 GHz at 1.6v by using LN2 cooling. So with some pretty extreme cooling the Phenom II does show that it has some legs in the clockspeed department.
While the Phenom II was OC'd using LN2, dry ice is a less expensive way to achieve ultra-low temperatures. Pictured is a typical dry ice setup. A liquid such as acetone or strong rubbing alcohol is used to immerse the dry ice, as these liquids freeze well below the 109.3F that dry ice sublimates at. Proper ventilation is required as the volume of CO2 that is released can quickly create a hazardous situation in a small room with poor air circulation.
The original Barcelona is a 65 nm part and really the first of its architecture. Since its release and the subsequent shuffling around of design teams, AMD has refocused their energy on delivering a design that would not only have a better per clock performance than the older part, but allow the design to scale in clockspeed on AMD's new 45 nm process. So far what we have seen shows that AMD has done very well. While the 3.0 GHz Phenom II will likely not perform anywhere near that of the new 3.2 GHz Intel i7, it will show very well against the older Intel Core 2 quads. Not only that, but we will see how AMD scales clockspeed in the future, as well as how they handle DDR-3 support early next year. With AMD's constant process improvement program, and tweaks to the Phenom II design that we typically see in the manufacturing stage, AMD could theoretically have a 3.4 to 3.6 GHz processor at moderate TDP levels (think 125 watts) that would more adequately perform against the mighty i7 within the next 8 months.
The big question is if AMD wants to pursue a clockspeed battle with Intel. I believe that AMD is holding their cards close to their chest in this case, and by not releasing a Phenom II faster than 3.0 GHz, they are not provoking Intel into a costly clockspeed battle. But when Intel releases faster parts next year, we can bet that AMD will have an answer for it at every step. I do not believe that AMD wants to get back the performance crown at this time, namely because they do not have a design that is head and shoulders above what Intel currently has. So they are content to be 2nd best, and keep Intel in sight in terms of performance and features. This way they can continue to carve a niche out for themselves and offer products that may appeal to enthusiasts, home entertainment, and gaming consumers. All the while keeping their manufacturing costs reasonable by not engaging in a clockspeed battle with Intel, which would only result in lower ASPs for both companies (something that AMD can not afford to do).
So AMD is pushing the "headroom" feature, which will appeal to enthusiasts and gamers. But they are also keeping TDP down as much as possible to attract regular desktop users as well as those who are interested in cool and quiet systems (underclockers, HTPC segment). Getting 5 GHz out of a processor which features 700 million transistors + is no small feat, even when using dry ice. Enthusiasts have already taken the i7 to 5.7 GHz+ on LN, and it will be interesting to see what these folks will be able to do with the Phenom II when it arrives.
For now, we have to sit and wait for the Phenom II to hit the market. Intel certainly needs the competition, and this product might just deliver enough of it to keep things interesting.
Update: The Phenom II
reached WELL over 5.x GHz (read: REALLY over) at 1.9v on liquid nitrogen (boiling point -321F/-196C at
1 atm). Testing looks to have been done on a Gigabyte 790GX
motherboard that is currently available.