Ivy Bridge processor availability

I think i found your answer. I could be ENTIRELY wrong here. But from what little research i did i think this is it.

Basically the i5-3570s is labeled as a OEM/tray microprocessor. Meaning Wholesale processors are not sold in retail boxes and are typically pre-installed by an OEM or reseller. Intel ships the processors to OEMs in trays so we refer to these types of processors as OEM/Tray processors.

So basically from what i read it sounds like Intel doesn't support the i5-3570s for retail sales.

Heres the links i found the info at.

Marked as OEM/tray microprocessor
http://www.cpu-world.com/CPUs/Core_i5/Intel-Core%20i5-3...

Explanation of How to identify a boxed vs. an OEM processor
http://www.intel.com/support/processors/sb/CS-030339.ht...

Again i could be wrong. So don't quote me. But i think it's right   hope it helps.

There is no shortage of Ivy Bridge CPUs, they are in full production.

http://ark.intel.com/products/65518/Intel-Core-i5-3550S...
http://ark.intel.com/products/65701/Intel-Core-i5-3570S...

the 3550S and 3570S (and probably most/all other S-variants) are listed as OEM ("Tray") only so you are not supposed to be able to find it in retail stores. These can only be purchased from Intel's official distributors in trays of 1000 so smaller distributors and retailers need to book orders before ordering trays to avoid getting stuck with a large unsold inventory.

Simply get a 3570/3570K. Most local stores will have those in stock or short order.

Both unoriginal1 and InvalidError are right. At this time they are OEM/tray only processors. The Intel® Core™ i5-2400s is out there which is close in performance to the Intel Core i5-3570s. Of course if you were to pick the Intel Core i5-3570K you could simply clock it down and get better power savings.

The enlightenments are appreciated. It's been quite a while since my last build and the hardware and marketing have changed. The proposed system is for HTPC and amature music production purposes, so a medium performance, quad core rig using the in-chip Ivy Bridge graphics is probably a reasonable compromise.
AFAIK now, it's possible to use the ASROCK H77 Pro4/MVP and downclock an unlocked IB CPU and save a few bucks and have support for 3 legacy PCI cards. Another choice is to buck up for a GIGABYTE GA-Z77-D3H, which is apparently a more robust PCB with a few more USB/PCIe connectors, but only 2 of the older PCI slots.
Some comments implicate the Pro4/MVP and other budget ASROCK boards as being 'flimsy'. It's been 9 years since I put together this P4 system and hope to get similar mileage out of the new build so, if true, flimsy might not work here. Thanks again for your gentle opinion.

I would not worry/bother about buying an unlocked chip to down-clock it since the chips already down-clock themselves with SpeedStep while idle and the "downclock" only affects the max multiplier for full-load.

What PCI cards are you so attached to as to require 3 PCI slots? Modern chipsets do not have native legacy-PCI support and must use a PCI-PCIe bridge chip to implement those so they are becoming uncommon. Today's HD-Audio chips are much better than AC97 so most people can make-do without a sound card. Graphics is pretty much the only common add-in board in today's PCs but with AMD's new APUs, even that might be about to become history for mid/low-end gaming.

Any modern Intel chip will be leaps and bounds faster than whatever P4 you had so if you managed to stretch a P4 for almost a decade, almost anything you can buy today should last a fair while performance-wise unless your everyday usage changes drastically. I personally have had good luck with Asus' mainstream series in the past and since I do not care about OCing or SLI/CFX, I would pick something like the P8B75-M or P8H77-M.

Thanks for a gentle reply. PCI MIDI synths/soundcards used to be common in making music on a budget as a good one can sound more realistic or have more flexibility than low-end software synths. It's quite possible that I'll find a way to do what is envisioned with software only (VSTs/softsynths) .... the PCI bit is just in case the software only way doesn't work out for me right away. I'll check out the Asus series. Thanks again.

I guess it takes a little good advice from people that are smarter than me. After looking into some of the Intel docs concerning the flex ratio, turbo boost, and power management, there really doesn't seem to be much point in seeking out an 'S' model. There are a few references of setting bckl ratios of 'locked' processors ONLY below the system nominal as long as it's within a certain range. With an unlocked CPU, there can be warranty issues if I mess up in the BIOS and over-heat the chip.
Anyways, the power savings would apparently be pretty small, so it looks as though an i5-xxxx'S' isn't very critical. The i5-3570K does have more Si for graphics than the other available i5 units and, as you pointed out, can be underclocked.