ECS 915P-A
| ECS 915P-A | |
| CPU Support | All LGA775 processors (only on rev1.1+ boards, Extreme Edition unsupported on rev1.0) |
| Northbridge | Intel i915P 'Grantsdale' |
| Memory Support | 4 slots. 2 x DDR (DDR400 max), 2 x DDR-II (DDR533 max), 2GB max for each type |
| AGP | AGP 'Express' |
| PEG16X | One slot |
| Southbridge | Intel ICH6 |
| Audio | C-Media CMI9880 HD Audio CODEC from ICH6 feed |
| Audio Connectivity | 8 port backplane analogue speaker |
| PCI Conventional | 2 x 32-bit 33MHz PCI 2.3 slots |
| PCI Express | 2 x 1X slots |
| IDE | 1 ATA133 compliant port from ICH6 |
| IDE RAID | None |
| SATA | 4 ports from ICH6 |
| SATA RAID | None |
| Networking | Realtek 8110S Gigabit Ethernet Controller, 10/100/1000Mbit |
| USB | ICH6/R, 4 x backplane USB2.0 |
| FireWire | None |
| Other I/O | PS/2, Parallel, 1 x Serial, floppy |
The 915P-A implements all the platform features that Intel brought to the table for the Pentium 4 recently, but what stands out is the graphics card support. ECS, as well as supplying a PEG16X slot for graphics cards, supply what they call an AGP Express port. It's basically a pair of bonded PCI Conventional slots (32-bit, 33MHz) to which an AGP graphics card can connect electrically, and run in PCI mode. That means the graphics card can't take advantage of features that AGP provided over PCI in the first place (remember, AGP is an extension to basic PCI in terms of functionality, not a completely new standard), but AGP cards can run in PCI mode since the electrical slot connector is there.
There's no AGP interface on the Grantsdale MCH, which is where the main difference lies, ECS's engineers coming up with a somewhat novel way to allow electrical AGP compatibility using the PCI interface present on the ICH6. If you look at the rear of a 915P-A, you'll see the traces from the PEG16X slot running to the MCH, while the traces from the AGP slot run to the ICH6, that houses the PCI interface.
So while AGP Express might insinuate something even more capable than 'regular' AGP, it's actually a lower performance implementation of AGP. Traffic from an AGP graphics card in the AGP Express slot has to travel via the ICH6 and its Intel Hub Architecture link to the MCH, before communication with the CPU can take place. Also, the AGP graphics card in a 915P-A can't use all the features of AGP that make it attractive as a graphics card interconnect.
You can't do DIME, a part of the AGP spec that allows the graphics card to access main memory, bypassing the CPU. There's no mapped and locked section of system memory for the graphics card to use as its own, known as GART. And the graphics card in the AGP Express slot has to share bandwidth with all the other PCI devices that communicate with the ICH6, since PCI is a bandwidth-sharing architecture. No one device can lock the bus for itself, in a strict sense. It can lock it for a single bus transaction, or set of transactions, but it can't lock it exclusively. At some point, if another PCI device needs the bus, the AGP Express slot will have to yeild and allow that traffic.
So it's not optimal, but if you're not heavily taxing the PCI bus, performance might be acceptable.
Finally, with regards to the graphics setup on the 915P-A, you can also use graphics cards in the AGP Express slot at the same time as any card in the PEG16X slot for PCI Express graphics cards. For example, as a means to getting inexpensive quad head DVI support in your PC, with modern GPUs, the 915P-A might be somewhat attractive.
Otherwise, the 915P-A is what we've come to expect from new P4 platform boards, with support for DDR-II (along with DDR), PCI Express for peripherals, and HD Audio. Four port native SATA support rounds things off.
It doesn't implement ICH6/R or the SiS180 controllers on the PF4 Extreme, for RAID support and even more disk connectivity, nor the FireWire400 support or three network controllers (including Wi-Fi) also present on that board, but the 915P-A sits in a different market segment.
