Ground

yeah I've by now found 2 45nm chips doing 4.5/1.2V and 4.83/1.33V, though by now I've also found a couple similarly crazy 32nm chips, though they are out of a far larger sample size (about 20kg of chips). Two of them do 5Ghz at around 1.4V.

have changed 2Gbit dies to 8Gbit dies on an HD 7870 before, but off course you have to stay with the same technology.

4 way sli isn‘t a thing anymore. 2 way is the max supported by modern stuff and thats where most boards stop. The only recent example I can think of is the msi godlike which at least supports 4 way crossfire. Also may I ask how 4 way sli is supposed to work with 3 slots?

so wait, you are worried about buying high end from a company because their low end isn't amazing? The Godlike (and Ace, unifi and creation) has pretty overkill vrms...

Degradation has been noticed at sustained 1.375V.

@kaibsora I had the msi x58-Pro as my first x58 board and can confirm westmere xeons work just fine in it. I would recommend throwing a fan on the nb heatsink though. It is a bit buggy with the x56xx xeons in the way that the uncore multiplier can‘t go below 20x (so at 200 bclk you would run 4 ghz uncore whch many chips can‘t do reliably), so if you get one either get an E5649 (I ran mine at 225x19 on that board since it doesn‘t have the issue) or an x5670 or better. yesterday fixed a couple boards, so my current collection of x58 boards contains: R2E (repaired, currently only 13 out of 16 phases working. Can probably get 15 working again) R3E (repaired, currently 5 out of 8 phases working. Can probably get 6 working) x58a-gd65 (repaired-ish, currently 3 out of 8 phases working. Going to epower this board since I can‘t see myself reasonably fixing it properly) x58a-oc (fully working) x58a-oc (dead, unknown reason. Hope to fix it) Foxconn Bloodrage (PCIe modded, fully working) I‘ve also had, but sold: P6T Deluxe (dead, never got it working) x58a-oc (fully working) x58a-ud7 (bought dead with vrm blown up, fixed to full working order) x58 Pro-E (fully working) EX58-ud3r (bought as dead, only needed bios update, fully working) still have a couple boards I really wanna buy at some point but most are too rare or expensive for me. In particular R3F, R3BE, Evga Classified 3 way, msi big bang.

So yeah, the voltage under load is usually the bigger issue (since thats when you see high current at the same time), so that shouldn't be as bad. Still not gonna last forever but I guess replacements are cheap enough... the testing at 1.55V was with LLC on on a Rampage II Extreme with an E5640 at 4.8 GHz (reject chip), I started losing stability after about 3 days with that setup. The chip I actually used for daily for a while didn't ever see that kind of voltage on ambient, it does 4.5/1.36V with LLC on. These chips are nothing compared to the strongest 45nm chips I've found so far though which have significantly stronger cores and sometimes insanely strong uncores too.

what are you using to cool the 990X at 1.53V? Some time last year I was doing some degradation testing and I saw rapid degradation at 1.55V... Shouldn't be much better at 1.53V...

x58a-ud9 and asus P6T7. The later one is especially cool since its normal height, just a little wider... (NB is under the big chunky heatsink - low res pic without heatsinks, enough to see whats going on under them...

are people still paying that amount of money for standard 1366 boards? In Germany low-endish boards (basic P6T, ud3r, msi x58 pro, foxconn flaming blade) go for ~50-60€ now, mid tier boards maybe 90€, older high end boards (R2E, Ud7) for 120€ ish and the very very best boards for 150ish (x58a-oc, R3E, though even these can be found for less)... Zen 2 and dropping mem pricing put a serious hit in the value of x58 as a platform...

the very best 45nm chips handily beat the best 32nm chips. I have a W3520 and i7 920 that run Superpi 32M at 4.5/1.2V, none of my 32nm chips (out of around 100 by now) manage that.

eh not really. Its good for 32nm multicore stuff, but for anything else (in my experience) even the Rampage II beats it easily. I've by now had several different x58a-ocs cold (still own a working and a dead one), and while they work well the main thing they have going for them is the great VRM they have. For 45nm benching Rampage II Extreme/Rampage III Black or worst case Rampage III Extreme are much easier to run and can usually get better results. I've done this score on a Rampage II Extreme on Cascade, can't get anywhere close to that with an x58a-oc with an otherwise identical setup. I've recently picked up a Foxconn Bloodrage to compare, haven't gotten around to test it properly. I did manage finding a really nice i7 920 on ambient, really hard to control on LN2, need to run it on cascade to see what it can actually do. 4.5/~1.2V seems to be my baseline for really nice 45nm chips since my W3520 does about the same. x58a-oc you can usually sell for 200+ on ebay btw. I usually get mine for far less on forums or classifieds. Also have an x58a-GD65, Rampage II Extreme and Rampage III Extreme each with blown up VRMs in various boxes that I have to get fixed, spent a couple hours yesterday trying to get the second x58a-oc working again. Bloodrage, signed x58a-oc and R3E at least fully work.

x99 with xeons works fairly well with Reg ECC. Pretty sure all asus boards at least, I've heard some got it to work on pretty much any board even.

are you testing with the xeon or the old i7? Most EVGA boards require a hardmod to work with the xeons...

Picking up 1366 for a daily hasn't been a good idea for at least half a year now, basically since DDR4 prices started dropping. Ryzen 1xxx series has been quite cheap for quite a while now... I'm not quite sure yet, but I could imagine x99 with Reg ECC and Xeons could get interesting once the first gen of DDR4 servers get decommissioned.