Granite Bay ?
Granite Bay, why ?.
Intel are having a busy day today. Not only is the Granite Bay chipset officially launched, we also have the 533FSB Xeons, along with Placer (E7505, dual-channel DDR for Xeons) and Plumas server boards being launched.
Granite Bay, or E7205 as Intel like to call it, is perhaps of most interest to us in the desktop PC world. Although it's technically positioned as a low-cost, dual-channel DDR-based server motherboard, notable first-tier motherboard manufacturers have seen fit to produce a retail desktop motherboard based on its technology.
So, what does it offer that our current crop of chipsets don't ?. The first and most obvious difference is the support for dual-channel DDR. We know that SiS' 655 and VIA's P4X600 are scheduled to offer the same support in a more flexible manner, but Intel are there first.
Think of the Pentium 4 for a second. The present processors generally work off a 133FSB. Using its quad-pumped FSB, it can use up to 4.26GB/s of bandwidth (533MB/s x 8) at default FSB speeds. Current chipsets, roughly speaking, offer the following supported theoretical bandwidth fills:
4200MB/s - PC1066 / RIMM4200 RAMBUS
2700MB/s - Intel i845PE / GE, SiS648, VIA P4X400
2100MB/s - Intel i845E
There's more to it than just that. Bandwidth efficiency, unbuffered performance, latency, and a number of other factors combine to ensure that those bandwidth figures are never truly realised. Still, our benchmarks have illustrated that bandwidth is king. RAMBUS is still the fastest solution at stock speeds, albeit not by much.
Now what if we could combine 2 channels of DDR266 (or faster) RAM. We would then, theoretically, see 4.26GB/s at 133FSB with DDR. Granite Bay attempts to do this by offering support for up to 4GB of RAM via 2 sets of twin DDR slots. The caveat, though, is that one has to use DIMMs of equal size and construction for it to work correctly. Additionally, one cannot use double-sided x16 DDR DIMMs, but find me someone who produces these in volume and I'll eat my hat. Everyone now seems to favour the 8-chip combination. You're essentially splitting any information between two modules and then allowing the Northbridge to retrieve the information from both modules at once, somewhat akin to IDE RAID 0. Granite Bay also works in single-channel mode, but, as you may have guessed, its performance lies in using its twin DIMM technology.
As you might have expected, Hyper-Threading support is available in this newest chipset. Finally, we see 8x AGP support (AGP3.0 specification) present. This may not be of that much use right now, but with faster cards and greater geometry being employed in games, the 2GB/s on offer may finally be realised. ATi's R9700. NVIDIA's upcoming NV30, and SiS' Xabre are all 8x AGP compliant.
The current ICH4 Southbridge is carried over to the Granite Bay chipset. So we get no inherent support for Firewire or Serial ATA. We'll have to wait for the ICH5 to surface some time next year, me thinks.
In summation, support for up to 4GB of unbuffered memory, more bandwidth than any DDR chipset currently available, AGP 8x and Hyper-Threading support gives Granite Bay a huge amount of potential. Can it eclipse the incumbent benchmark champion, the i850E chipset, as the performance leader ?. Read on.
