Scrypt coins like Litecoin have not been profitable to mine with any GPU setup (you don't even mention your GPU, the HD and RAM don't MATTER) even with free electric for YEARS now.

 You might want to look into the NiceHash miner.

Crossfire will actually HURT hashrate a lot of the time when it is active.

Just turn it off (and check, sometimes AMD drivers want to turn it ON without asking you).

 Most modern 80Plus rated PS achieve maximum efficiency near the 50% load point - but you then have to worry a bit about the extra cost.

 In your case though, a 400-500 Watt PS tends to be cheap enough to not worry about "too much PS" and how long the PS will take to pay off the extra capasity.

I suspect Bitmain will sell as many L3+ as they can get chips made for for as long as folks buy them as fast as they can make them - which WILL slow down when the current profitability level drops quite a bit.

 This will take a while though - even the bloody GRIDSEED GC3355-based miners have gotten to be profitable again at current Litecoin price vs current difficulty.

 I also suspect the entire reason they were willing to do the L3 at all was that sales of the S9/T9/R4 had finally dropped to the point that they COULDN'T sell them as fast as they could get the chips, so they had some "spare foundry capasity" available to do something else on.


 I keep wondering if they're working on an X11/X13/etc chip design to go head-to-head against the Baikal, for when L3+ sales start stagnating.

Mostly selling - as usuall on most of my mined coins.

Even though the diff doubling in the last month-and-change, the PRICE went up enough to make it much higher profitability than any other time in the last 2 years or so.

Nicehash supports "mixed" setups like that without issue.

 It tends to be less stable than "pure" rigs, but it DOES work - and setting up mixed setups is the one place Windows (7 and 10 anyway) does a much better job than LINUX.

SHA256 - aka the same algorythm Bitcoin uses, so any "bitcoin" miner should work on it - and it's probably already ASIC dominated.

 you'd have to use a pool specific to that coin though.

GTX 1070s in particular are good at ZEC, showing higher hashrates than RX 480s at similar efficiency and fairly close on cost/hash - but that's an uncommon case.

 On ETH, they are very close on hashrate and efficiency, but the ALMOST DOUBLE up-front cost of a GTX 1070 would make them a bad choice for ETH.

 There are other choices where the 1070's higher price is easily justified by it's much higher capability, but those tend to be small-volume coins while the RX series generally does as well to better on most high-volume GPU mineable coins.

GTX 950 and GTX 960 are generation-old and less efficient, ignore them - the GTX 1050 will mine better than the 950 and very close to the 960 at MUCH lower power draw.

The real difference between the RX 5xx series and the RX 4xx series is that AMD moved to a different process (still on the same process NODE though) that allows the GPU to clock somewhat higher at a slight cost in efficiency compared to the older version of the same GPU on the other process.
 The memory options between the 2 lines are THE SAME, except I don't think anyone is bothering to make 4GB 6600Mhs memory clock cards any more.

 The other difference is that the 4xx series seems to now be out of production, and only "remaining stock" and used/refurb cards are available.

 The only ASIC available for LTC that are NEW CURRENT PRODUCTION at this time are the Antminer L3/L3+ and the Innosilicon A4.

 Everything else is older, and noticeably less efficient than the A4, much less the L3/L3+

 if I buy a L3 or L3+, it would be direct from Bitmain the manufacturer as anyone else marks up the price a LOT.

 Ryzen is actually proving to be competative on efficiency for XMR vs any GPU (possible exception for the GTX 750 ti, but that thing seems to have hit THE sweet spot on XMR).

 Some of the more modern Intel CPUs are pretty efficient too.

 pre-Ryzen AMD CPUs though are definitely NOT XMR efficient by current standards, nor are pre-Maxwell NVidia GPUs or pre-RX AMD GPUs (possible exception for the Fury/FuryX/Nano?).



 OP, keep in mind that your particular I7 model is a few generations old now, and at LEAST one if not 2 process nodes behind current state-of-the-art - of COURSE it is less efficient than stuff running on a CURRENT process node.

 I was still mining ETH on some 2GB cards into late Febuary or early March.

 On the other hand, the "exceed 4GB limit" will probably never happen on ETH (it should eventually on ETC) as ETH is supposed to be going Proof of Stake long before the DAG file gets that big.


 For gaming, 4GB works just fine on my 1440p monitor running Ashes. More and faster RAM (8GB cards seem to always have 8Ghs ram, 4GB usually has 7 and sometimes 6.6) wouldn't hurt for a future-proofing gamer though.


 And no, most 4GB memory will NOT clock to 8Ghs - a lot if it does very good to get to 7.5

Lower end NVidia cards aren't bad to mine on - but the Titan line for it's performance level has ALWAYS been way overpriced, and right now the 1080 Ti is pretty much a match across the board on performace vs the current Titan X Pascal for roughly 2/3ds the price.

 If your mining room is 10 degrees F or more above ambient, you don't have to worry about humidity.

 In my case, even when it's raining outside and I have my largish Brisa Evap cooler running, I only see 40% or so RH at the most, and most of the time closer to 30% - but that's with somewhat over 15KW worth of mining gear running.

 

Keep in mind that Litecoin difficulty has DOUBLED in a bit more than a month, due in large part to massive sales out of Bitmain of the L3/L3+ = and you can anticipate the difficulty continuing to rise quite quickly for the same reason for at least a couple more months, even if Litecoin prices flatlines in the current 25 dollar range.

 Scrypt profitibility RIGHT NOW, even so, is higher than it has been anytime in the last 2 years - but that's not going to stay that way unless Litecoin price continues to outpace difficulty growth.


 On the other hand, those of us with older PAID FOR rigs like my A2 farm are LOVING the current profitability....

Rough ballpark half of my current hash is currently pointed at Nicehash, which cashes out to my Coinbase instant sell address - this is my "pay the monthly bills and buy food/gas/etc with" account at this point.
The other is kinda all over the place, but ends up getting converted to BTC (or right now just stays at LTC) for use later, usually for buying additions to my mining farm.

I used to have to use some of "the other" to pay bills with too, but the recent runup on most altcoins has been nice for saving up for growth (I plan to move into a new space soon with MUCH MORE POWER and better ventilation capability, just waiting on the current tenant to get around to moving out).

 I've seen up to 16 PCI-E 16-bit slots on a motherboard, but it was a server-specific passive backplane style board and not real suitable to try to mine on AND bloody expen$$$$ive.

 
 It's entirely possible to run NVidia and AMD gpus in the same machine - but it tends to be less stable than a "pure" rig.
 Windows 7 or 10 does this easily, LINUX can do it but need a bit of custom work on installing the drivers.


 The Radeon Pro Dual is 2x Fury Nano on one physical card - can't clock it QUITE as high as a Nano due to the higher heat generation in less space, but can get pretty close per multiple reports.
 

16.10.1 (I think that's the WHQL cert version of the 16.10 range) works reasonably well in my testing of it.

 ALL of the "relive" versions I have ever tried have been lower performance bloated JUNK.

 On the other hand, there is no miner more efficient than the L3/L3+ right now, so folks will STOP buying them when they get to be low-enough profitability.

 Also, Litecoin price has kicked up about 6 times in the same timeframe that the difficulty has doubled - and Bitmain seems to be having the same "limit of chip availability" issues with the L3/L3+ that they've shown with the various S9/T9/R4 batches limiting HOW MANY they can make, which should keep the difficulty increases somewhat in check for a while.

 For reference, my A2 farm is MORE profitable right now by a wide margin than at any other time since I bought the things except for about a 1 day period right before the last diff jump - despite the massive increase in diff since the Innosilicon A4 was first introduced. Gonna take a major Litecoin price drop and/or a LOT more of a diff jump before the A2 gets to be unprofitable, much less the Titan A4s or L3/L3+ units.

It can be worked around using Afterburner and it's "ULPS" override setting - usually.