Intel i815 / i815E Motherboard Roundup - August 2000by Mike Andrawes on August 3, 2000 5:25 AM EST
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As we've mentioned previously, the i815 is the first chipset from Intel that we've really liked since the i440BX, which was released over 2 years ago - an eternity in today's computer industry. As evidenced by ABIT's recent release of the BX133-RAID, the i440BX is alive and kicking, thanks to the inability for Intel to come up with a viable chipset alternative. Nevertheless, the i440BX is definitely starting to show it's gray hairs, especially in comparison to other recent chipsets that include AGP 4X support, Ultra ATA/66 (and now 100), official 133 MHz support, etc.
Well Intel has finally brought all of these features to market without requiring the use of RDRAM. Unfortunately, Intel's emphasis is still clearly RDRAM solutions, so the i815 has been "crippled" a number of ways. It's not clear whether it's for cost reasons or simply to limit the performance of PC133 SDRAM solutions in comparison to RDRAM solutions, but the fact remains that there are some clear limitations of the i815.
First and foremost, the i82815 GMCH (Graphics and Memory Controller Hub) contains integrated graphics, derived from the defunct i752 chipset, that shows Intel's clear focus for the i815 - the low-end market. That means it's pretty much the same graphics core found on the i815's predecessor, the i810, which in turn means that it's not very useful for anything beyond 2D applications as we've shown previously. Fortunately, the i815 does offer an AGP 4X slot for upgrading to your favorite video card.
Second, the memory controller on the GMCH also limits you to a maximum of 512MB of RAM, once again showing Intel's focus towards the low-end market. While 512MB may seem like a lot for now, it may very well seem a bit constraining as you begin to upgrade your system, especially if you plan to keep the motherboard for more than a year. Considering that the memory controller on the i440BX could support up to 1 GB, this definitely seems like a step back. An artificial limitation by Intel? Only Intel's engineers can answer that question
Once again, the GMCH jumps in with it's third major limitation - while the the i82815 GMCH supports 6 rows of memory, enough for 3 DIMM slots, Intel has only qualified it to support 2 PC133 DIMM's at once. In a board that follows Intel's specs, as soon as you drop in a 3rd DIMM, the board will fall back to PC100 operation. Fortunately for us, motherboard manufacturer's know we like to tweak our systems, and many boards will allow setting the memory speed manually. Yet another sign of "artificial" limitations by Intel? In this case we did notice a drop in stability with many boards when running 3 DIMM's at 133 MHz.
Interestingly enough, Intel has also chosen to not allow PC133 memory speeds in conjunction with 66 or 100 MHz FSB CPU's. Now, we know that Intel should be able to do this, since they're able to support PC100 with 66, 100, or 133 MHz CPU's. Another "artificial" limitation by Intel? We wish we knew the answer too.
The last little trick Intel has managed to pull on us with the i815 chipset is to limit the AGP Aperture size to a maximum of 64MB. We've seen settings of 128 or 256MB on i440BX and VIA 133A motherboards, and it once again seems like Intel is doing this intentionally to cripple the i815. That means your graphics card cannot use more than 64MB of system memory for AGP texturing, but fortunately, we've yet to see a performance loss due to this limitation. And we most likely won't in the near future since AGP texturing is simply entirely too slow. So don't blame your motherboard when you can't set this higher than 64MB, blame Intel.
Less obvious, and potentially less important for most users, is that fact that the i815 is also not SMP capable, meaning that Intel is still without a solid 133 MHz FSB solution for high-end servers or workstations. The i820/i840 is not exactly cost effective thanks to the high cost of RDRAM that becomes very significant when you're talking about large amounts of RAM. For now, the best bet is to stick with an i440BX board and 100 MHz CPU's or consider an SMP VIA 133A board.