Monday, July 30, 2007

Secret of Intel Core Duo CPU

I have 2 systems running with Q6600 Intel Core Duo Quad cores. They can crunch a lot of numbers and last price I saw for them online for only $290-310 each. Both these systems use a Asus P5B-VM uATX motherboard, 2GB of DDR2-800 RAM, Enermax Liberty 400w modular power supply, 80GB SATA drive and Ubuntu Linux 7.04.

The Sneaky Secret of the Core Duo
I have since discovered the secret of the Core Duo - it is a rather smart (but sneaky) marketing move by Intel. My first Core Duo was a E6300 running at 1.8Ghz. I remember reading all the magazine reviews that showed the 1.8 kicking the butt of AMD's running at 2+Ghz. It was like Intel had found a new secret sauce for making processors. The magazines played along and all bemoaned how AMD was doomed unless they could counter this brilliant new secret sauce.

But I now know the secret. At work I happen to have a few Pentium D Dual-Core running at 3.6GHz - a nice number; just happens to be twice the rated speed of the E6300. However, if you run some old-fashioned MIPS/FLOPS hardware benchmarks - the kind magazines NEVER run anymore - you will find the Core Duo at 1.8Ghz pretty much matches the Dual-Core PD at 3.6Ghz at basic integer tests, and does only 50-60% as well at the floating point tests. So clearly, the Core Duo E6300 has portions of the chip running at 1.8GHz and portions running at 3.6Ghz (double-clocked). Such technology is easy these days - 10/100Mhz Ethernet hardware runs with a 25Mhz crystal and uses a clock multiplier to gain the 100Mhz cycles. Intel must be using a 1.8Ghz crystal and clock multiplier to run portions of the chip at 3.6Ghz. This also makes sense given the Core Duo concept came out of Intel's "mobile" design team - people who realized that running different portions of the chip at different speeds helps cut power usage and heat generation.

The really brilliant (& somewhat risky) marketing move was to call a chip like the E6300 a "1.8GHz chip" even though it ran at 3.6Ghz ... this is what caused the big media back-lash against AMD. Had the magazines tested the E6300 as a 3.6Ghz chip ... the test results would have been disappointing compared to a true 3.6Ghz Pentium D dual-core. It would have shown the Core Duo as a chip which sacrificed performance for lower power.

However, since it was called a 1.8Ghz chip, all the tests were showing up as 30 to 70% "better than expected". Magzines had no problems with the apples-to-oranges comparison of a 1.8Ghz Intel out running a 2+Ghz AMD since the AMD had (on paper) a higher clock rate. But what they didn't understand was that they were actually comparing a slightly crippled 3.6Ghz Intel against the 2+Ghz AMD; of course the crippled 3.6Ghz chip would beat out the 2+Ghz AMD

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