Frankly, I am really perturbed about this. Years ago, all cases came with a "case speaker" used to "sound" error beep codes. Then, more and more motherboards started to integrate tiny piezoelectric "button" speakers on their boards. So case makers, seeing an opportunity to save a couple pennies, stopped including them with their cases.
But now I am seeing more and more motherboards (including my new Gigabyte GA-Z77X-D3H) without integrated speakers leaving users in the lurch.
Yes, that mini onboard speaker will work but I might suggest you rummage through any old cases you have laying around and see if you can't pull one out of there. If you order on line, unless you order something else with this to qualify for free shipping, you are going to end up paying over $10 for a $.25 speaker.
Add CPU power - System boots to Windows.
...do you think the issue is just hiding now and will return?
My "guess" (if no foreign objects under the board) is you had a loose connection - assuming now, you have all your devices connected (data and power) and it still works.
Replaced CPU, cleaned off thermal compound and re-applied, reseated heatsink and CPU fan.
Was that the OEM cooler or the aftermarket cooler? Do note you void your Intel warranty using an aftermarket cooler on retail "boxed" CPUs that come with OEM supplied coolers. Of course, that is not a concern for many, but I do note motherboard designers cluster heat sensitive devices around the CPU socket so they too can take advantage of the expected downward
firing OEM CPU fan. Side firing fans may not provide expected cooling to those sensitive motherboard components.
Since cooling is the responsibility of the case, and the CPU fan need only toss CPU heat into the cool-air flow through the case, I would suggest you use the OEM cooler - at least until you are certain this problem has been resolved. OEM coolers today are excellent coolers - fully capable of cooling the CPUs they come with, even with mild to moderate overclocking - and without voiding the warranty. Note too that only OEM coolers cover replacement of the CPU for the entire 3 years of the CPU warranty. And OEM coolers are warrantied for 3 years while most aftermarket coolers are for less. That CoolerMaster, for example, is only warrantied for 2 years, and no way CoolerMaster will cover damage to the CPU, in the [admittedly rare] event damage occurs.
Again, many enthusiasts don't care about CPU warranties, and that's fine as long as we understand the consequences. But I do want to reiterate that OEM coolers today can hold their own, and any perception that they are inferior or incapable coolers should be dismissed as false.
The only time I don't use OEM coolers in any of my builds is when building passive (no fans) cooling for PCs to be integrated into home theater systems - where any
fan noise is unacceptable.
BTW, I like your way of thinking. I too like Gigabyte and with my new Gigabyte board I bought a Corsair Carbide 300R case (looked at the 400 but I am not into fancy lights on my cases and I did not need that much extra space. I typically go for Antec cases as I have never been disappointed with them but I thought I would try a Corsair this time - considering their reputation for quality RAM and PSUs. I like the Corsair case, but frankly, the fit and finish is not up Antec standards. I need three hands and a strategically placed tongue to ensure all the panel keys line up correctly to ensure the right side (back of the motherboard) panel cover slides in exactly right. And some of the vent covers are secured in place by loosely bent metal tabs. My top vent was loose and wiggled around until I bent those tabs over a bit more. And concerning the tabs, a couple had jagged edges that could tear unsuspecting knuckles - minor quibbles, but still. Nice looking case however (though I expect a case to sit discretely off to the side and NOT draw attention to itself - so looks are somewhat secondary for me), with lots and lots of large (120 - 140mm) fan options. :)
And since I put my towers near the floor, the front-top power/reset buttons, audio and USB 3.0 ports means I don't have to crawl on the floor to plug in a memory stick! :)