Intel Xeon E5s pruned for single-socket workstations
A place to plug in your discrete GPU
Intel's "Sandy Bridge-EP" Xeon E5 server chip launch extravaganza  is not just about servers. It also includes some chippery for their forebears: old-fashioned, heavy-duty, desktop machines that are still called workstations.
Intel usually has a variant of its single-socket server processors – in years gone by, the Xeon SP and then the Xeon 3000 and now the Xeon E3-1200 – geared up for double-duty as processors for single-socket workstations. Last April, when the Sandy Bridge family of chips were first making their way into single-socket laptops, desktops, and servers with the four-core Xeon E3-1200s , all models of the chips could be used in single-socket workstations, particularly the slightly more expensive variants of the Xeon E3s that had Intel HD Graphics 3000 GPUs built in.
That extra GPU pushes the watts on the E3s up to 95 watts, compared to 80 watts without it. The 3.4GHz E3-1275 with the HD 3000 GPU on-chip was probably the best choice, at $339 each when bought in 1,000-unit trays. This chip has only 8MB of L3 cache on chip, as most of the E3s do. The E3-1280, which does not have HD graphics and which spins at 3.5GHz, costs $612 and is a silly considering the lack of appreciable performance that extra 100MHz gives.
If you want a more powerful discrete graphics card, more CPU cores, higher memory capacity, and more I/O bandwidth, then a strong case can be made to go for a single-socket Xeon E5-1600 processor. You've got three options, as you can see in the table below:
New Xeon E5-1600 workstation CPUs versus alternatives
At 130 watts, the Xeon E5-1600s run quite a bit hotter than the Xeon E3-1200s. The four-core E5-1620 – at $294 – has a little more L3 cache than the E3-1275 and runs 200MHz faster, too, for less money. (It does not have an integrated GPU, however.) The six-core E5-1650 is a better option than the top-bin E3 part for a workstation, too, provided you don't mind the extra power draw, and at $583 it is very reasonably priced compared to earlier Xeon 3000 series or Core i7 alternatives also used in workstations in the past two years. (Those comparisons are meant to be illustrative, not exhaustive, of where Intel was positioned when the Xeon 5600 processors for two-socket servers came out.) Unless you need the L3 cache memory, it is hard to make a case for the E5-1660, at $1,080 a pop.
And if you are feeling rich and can just go to a two-socket Xeon E5 machine, consider this: The new E5-2687W runs at only 3.1GHz and kicks off 150 watts with its eight cores up and humming, and it costs $1,885. To build a two-socket machine, you are looking at close to four grand for the processors alone. That's a lot of dough that could be spent on a bunch of GPUs if the workload is more about visualization than calculation. And even then, maybe OpenCL and CUDA could help there, too, on top of CPU-GPU hybrids. If it works for the largest supercomputer clusters in the world, maybe it can work for your workstation apps, too.
The E5-1650 offers about 40 per cent better bang for the buck than the Xeon 3000 series in terms of raw aggregate clock cycles, and costs less than half of what the new E5-2687W does on a per clock basis. (Multiply the clock speed by the number of cores and divide it into the price to get a ratio.) The E5-1620 is right in there with the E3s from a year ago, with a little more oomph as well as more memory and I/O capacity. ®