First desktop CPU SMT Packaging and New Thermal Barriers

For Pentium 4 parts up to 2 GHz Intel will maintain 423-pin PGA socket packaging, we learned at IDF, but for higher than 2 GHz parts Intel is moving to a 478-pin microPGA socket. This will be the first desktop CPU with an SMT package instead of a through hole design. Intel expects the new packaging to be more OEM friendly, and allow for 1 layer versus 4 layer board designs. The microPGA package will have a 50 mil pin pitch versus the 100 mil for the PGA package reducing pin inductance and allowing for better frequency scaling.

Intel's on-die thermal monitor for the Pentium 4 is also proving to be controversial. The monitor is meant to measure and sense actual chip temperatures, as opposed to spikes during peak performance. When the chip gets too hot, the on-die thermal monitor modulates the clock signal with a 50/50 duty cycle. Intel claims that this should not happen in practice, and that if it were, it would not adversely impact performance. However, the company seems to countering concerns among OEMs and working to educate its customers on this feature.

Obviously, Intel has a lot of work to do in order to both educate, and assuage its OEM customers as it moves to higher frequencies. The company is going into territory very unfamiliar to the PC industry, and with the enormous market for desktop CPUs, it has to address a very broad customer base that is more concerned about the impact on price, and performance than the complexities of high frequency circuit design. This may very well be Intel's biggest challenge in moving OEMs to higher frequencies in the next two years.