Hi--I am running an X58 EVGA 'E770 Classified 3' mobo with an i7 950 CPU. Recently I was getting a lot of game crashes and  thought I maybe had CPU issues. After much tinkering, I seem to have resolved the issue(s) without changing my CPU, but started checking on the availability of a replacement just in case. I came across many different models of the X58 Xeon models at pretty affordable prices online. So, I am considering to pick one of those up as a replacement to get a little performance boost on my aging system. I am considering three different Xeon models--x5690, x5677, and x5687. The first two are on the EVGA CPU compatibility list for my board, but the x5687 is not. They are all socket 1366. I am leaning towards the x5687 because of the current price vs performance. The x5690 would probably give the best performance (maybe) as it is 6 cores vs. the other two models being 4 core models, but it is about three three the price. Also, although it is only 4 cores, the x5687 is a faster 3.6 Ghz, compared to the 6 core x5690 @ 3.46 Ghz. The x5677 is a quad core @ 3.46 Ghz. So, I would probably like to buy the x5687. I am wondering if anyone has tried that processor on the 'E770 Classified 3' without any issues? I am thinking it should work, but would like to know for sure before buying. Not being on the compatibility list may just mean that EVGA never tested that configuration. Other boards in the EVGA X58 line needed a mod to support any of the Xeon (Westmere) processors, but the 'Classified 3' supported at least the Xeon models on the EVGA list (see here and scroll way down--https://www.evga.com/support/motherboard/legacy/) . This comp is being used for gaming, and general computing needs, and still holding up well. Thanks in advance for any help.
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System specs: EVGA E770 Classified 3 (x58)--intel i7 950--EVGA GTX 970 SSC x 2 SLI--Corsair Dominator 1600 Mhz (12Gb)--WD HLHX Velociraptor HDD (379 Gb) x 3--Corsair AX 1200 PSU

@ Nofearek9--Thanks. I have never overclocked this system. Kind of a shame in a way, as this board was a great overclocker in reviews. It's just that the whole OC process on the X58 just seemed a bit overly complicated. At this point I would be a bit concerned that the extra stress on the VRM might be a bit more risky on an 8 year old board. Even if I build a new system in coming months ( I have an EVGA X99 Micro 2 in storage--short on $$ to build it up) I would still like to keep the 'Classified 3' running as a backup system, and for general computing use as long as possible. Even with no OC it still performs very well--yesterday I was getting a steady 95 FPS in 'Metro Last Light Redux' (no dips at all) with EVERYTHING maxed except SSAA which was at 2X. So re the Xeons--not sure I would want to trade a Ghz. in stock speed to gain the two extra cores as most games do not take advantage of more than 4 cores anyways--but I will give that some thought. 
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System specs: EVGA E770 Classified 3 (x58)--intel i7 950--EVGA GTX 970 SSC x 2 SLI--Corsair Dominator 1600 Mhz (12Gb)--WD HLHX Velociraptor HDD (379 Gb) x 3--Corsair AX 1200 PSU

Thanks Bill1024--I see that the W3680 is not on the supported list either (the W3580 is). So, as I thought some processors not on the list are compatible. Don't really know what I will get yet. I will perhaps decide over the weekend so I can get something ordered. In the running are the X5687, 5677, 5690, and now maybe the W3680 as well. Are those others unlocked as well? Not sure if I want to get into an OC with this older board, but who knows...it has been the most stable board I have run with no issues I couldn't fix. When I looked at guides on OCing this board it looked kinda complicated. Is it actually pretty easy? Thanks.

Keep in mind if you use the buss, when you raise the buss, you also increase the memory speed so you have to lower the memory setting.
Then raise the buss watching memory speed.
Been a while, I sold off my x58 boards so I can not look at the BIOS now.
But it really was not all that hard to do. You can do it.

A little bit to digest there in my presently slow moving state on a Saturday morning. I am going to check back here later today and read all that again. Are you giving all that would need too be adjusted bios-wise above, or are there other settings that would need to be changed as well? I have a few guides bookmarked (some from here). When I looked at them years ago I just did not want to bother memorizing all the voltages, etc. as this system was giving great performance as it was. I wanted this machine to last--no OC means less risk likely. I was using 580s back then, but have moved up to the 970s. And my 950 might be holding them back a bit at times.

No advantage really, get the W3680. 
I sold it I do not remember which classified3, it did have a molex for the GPU extra power.
The EVGA SLI3, FTW3 and classified3 will take E,W and X series LGA 1366 CPUs both 4 and 6 core.
The W36xx do not have to worry about the ram limitation issue either. X series had an issue with higher than either 8x or 10x, can't remember which
I do believe the core name is Westmere. 
 
You can look up the specs here. Type in the CPU you want to look up in the top Right corner
http://www.cpu-world.com/...%20(BX80614X5660).html