Monday, March 30, 2009

Upgrading to an Intel Core i7 920 and Asus P6T motherboard

I get the itch to upgrade my PC every now and again. Usually I ignore it. I generally refuse to upgrade until I can at least double the performance of my existing system.

Fortunately (or unfortunately depending on your point of view) Moore's Law is hard at work; every few years the jump in performance becomes significant enough to justify an upgrade under my totally unscientific, rule of thumb doubling requirement.

This time around it's upgrading from a single core Athlon 64 (2.4GHZ) to an Intel Core i7 920.  As is usually the case upgrading the CPU meant that I had to upgrade the motherboard. This time around it was also necessary to upgrade RAM since the board I went with (an Asus P6T) doesn't support DDR.

The Core i7 architecture features some major improvements over its predecessor Core 2 architecture. Others, including Intel, have gone to great lengths to describe these improvements so I won't reproduce their discussions here.
The 2 architectural improvements that stand out the most to me are the new Quick Path Interconnect (QPI) and the return of HyperThreading (HT). That's right, HyperThreading is back with a vengeance. Before the Core series, which dropped HT, it was all the rage as it allows a single processor to execute 2 independent instruction streams simultaneously.

Quick Path Interconnect (QPI) is similar to AMD's HyperTransport except that its faster and transfers larger data chunks (bit-width). HyperTransport was responsible for AMDs lead in performance for the previous 3 or 4 years. Even at the same clock speed Intel CPUs couldn't get data into and out of the CPUs fast enough using the already overcrowded North and South bridges. When AMD went multicore the gap widened; without HyperTransport data had to be passed from core to core. Hypertransport provided a direct core to core connection at speeds much faster than anything the Core 2 series could hope to match. All of that is potentially wiped out by Intel's introduction of QPI.

Since I wanted to do the upgrade as cheaply as possible I've reused as much of my existing hardware as I can. The CoolerMaster Wave Master case, shown below, has a detachable motherboard tray to simplify mounting motherboard on the standoffs.


After removing the unused standoffs, which were shorting the board, the P6T fits nicely onto the tray. This Asus board shipped with an insulated back panel:


The Asus board's colored DIMM slots showed which slots were paired (shown below). The Gigabyte board had a chart to convey the same information but I prefer the Asus approach since it doesn't require me to refer to the manual the next time I upgrade RAM. Also, the gigabyte board only had 4 DIMM slots.

One final feature that anyone building a PC can appreciate is Asus' QuickConnect feature. Connecting the front panel to the header pins on the board (e.g., power sw, reset, speaker, hdd LED) has always been difficult and only becomes more difficult as our eyesight and dexterity fade away with age. Asus ships this board with an labeled extender (shown below) that can be pre-attached to the front panel connectors then mounted into the header board. Thanks Asus!!

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