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LOSTCIRCUITS	SHORTCUTS: The Slot Race At One Glance What You Get VRM and Layout Thermal and Power Management Integrated Peripherals, BIOS Installation and Overclocking Test Configuration, SPEC ViewPerf Multi Display Competition Final Thoughts Discuss this article in the LostCircuits Forums
ASUS P5W64 Wall Street Qartet Professional We Avoid Temptation
(Review by MS, November 16, 2006)

The P5W64 WS is somewhat unusual in its layout in that, as mentioned, it features four physical PCIe x16 connectors. Physical means that the connectors have the x16 form factor / length and, thus, can be populated with x16 PCIe extension cards. In the majority of cases, this will be graphics adapters. Electrically, the top connector has x16 capabilities, the second and fourth connector each has x8 capabilities and the third slot is hard-wired to the south bridge for x4 connectivity.

We mentioned earlier that the MCH features two separate PCIe x8 controllers (see picture above). As in the Intel reference design, one of the controllers is hardwired to the top PCIe slot, the second controller is routed to the IDT PRECISE 89HA0324PS connector switch. The 0324 part number means that the switch multiplies an 8 lane input into three outputs for a combined 24 lanes connectivity or 12 GBps aggregate switching throughput. That means that the 8 lanes are either going to the upper slot where they are combined with the first PCIe x8 link from the MCH to x16 connectivity, or else they are routed to the second and fourth slot. Keep in mind that in this case, all three slots will vie for the arbitration similar as in an old-fashioned PCI interrupt scenario where only one slot can be active at any time. The result is two connectivity scenarios, namely:

Unfortunately, the single-slot spacing makes it extremely difficult to find any current even midrange graphics cards that could populate all four slots, the heatspreaders are simply in the way. Two cards are still manageable, even in adjacent slots, since they will bend enough to fit. With three cards, things get really hairy, we tried two ASUS n7800GTs with one adjacent nVidia QuadroFX 1400 with the result that the heatsink on the lower n7800GT shorted the surface components on the Quadro FX1400's upper face.

           

Granted, this is not always going to be an issue but we thought it would be worth mentioning just as a precautionary measure. Also, for the record, we caught the issue before reconnecting the system to power, so no damage was done. One solution is, of course, to use slots 1,2 and 4 only but that may defy the purpose of the board.

Related to the restricted space is the issue of reaching the locking latch. In the case of the lowest slot, once the system was in the case, it was impossible to reach it at all - the quick and dirty solution was to break off the lever altogether (accidentally but unavoidable). Even the locks for slots 2 and 3 are barely reachable with cards mounted and in the least case require removal of the lower cards in order to gain access.

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