Most GPUs blow very little out the exhaust holes in the backplate.  Maybe the ones with the old hairdrier coolers on them, but not the type with the 2/3 open fans.  They dump their heat to the case, so adding a fan is ideal.

Yeah, but nothing you've included in your list holds you to SHA256, which is what the previous poster was implying.  You could mine anything you like with a GPU.

Difficulty just means you get bigger chunks to work on, which means you've less network bandwidth in use. 

What?     There's nothing mentioned in this thread about anything that traps him in to SHA256? 

Maybe it got too hot and it's wings melted?

If you know linux, there's no reason you can't run one of the small mining setups off a USB stick.  Something like BAMT https://bitcointalk.org/index.php?topic=28967.0 - I've never tried it, but if it works, then you don't need a HDD.

PSU, well if you're just going for the two card, a decent 500W will do you.  If you plan on adding more cards in the future, then you're best buying something a bit heavier to start off with.  When I was mining with two cards (a HD6970 and HD5870) on a Celeron G530 machine, I was using a OCZ 500W PSU which worked perfectly. It was very cheap, about £30.  I also used a really, really cheap Deer PSU which I had lying about, it worked OK but smelt funny after a while.  

Why are you trying to use an Intel Celeron in an AMD FM2 board?      

FM2 is a bad choice too, just get an AM3+ board - all FM2 adds is the ability to use a CPU with built in GPU, which you don't really want.  Go with a AM3+ and a cheap Sempron 145.

The 5850 cards would need to be cheap, because they don't really give much performance.  I get about 380MH/s out of a 5870, but it's hot, noisy, and a bit shit.  I'll be binning it when it dies (not long, fan is knackered).

So, basically, everything you've got listed there is the wrong choice.

If someone's still controlling your computer, then you haven't disconnected it from the internet, have you.

For the hard of thinking:
DISCONNECT YOUR COMPUTER FROM THE INTERNET!

Thanks, will give it a go. 

Finally got my mining machine running again (damned AMD drivers!), but I'm getting quite a few "unknown-work" rejections.  They seem to come in waves, closely followed by cgminer dropping the connection to the proxy.

Proxy is running on my home server.

CGMiner is 3.1.1

Should I just connect straight out to the pool?

Just upgraded to Windows 8 on my mining rig.  I've now got a HD5870, a HD6970 and a HD7850 all mining happily together with minimal effort.  Windows 7 was a nightmare for me with this hotch-potch of hardware.

Found it: https://github.com/CryptoManiac/stratum-mining-proxy

Is there a mining proxy for this pool?  I know you have one on the LTC side of things, but I'd appreciate one for the BTC.    I get a lot of stales from my slow miners if I don't use the proxy (plus I'm mining through a 3G connection during the day which sucks).

I use GUIMiner in my work PC for running a Quadro 600 and a HD7750.  Could never get cgminer to play ball with the two different types of card.

Why?  What's wrong with the other GUI miners?  You know, the ones with features and stuff? 

Windows 7 x64 Pro
AMD FX8320
Asus SABERTOOTH 990FX
HD7850 (Asus)
HD6970 (Powercolor)
HD5870 (Powercolor)

When I try and run CGMiner, it just brings up the "CGMINER.EXE has stopped working.

I've also tried GUIMiner, it just starts and quits. (Not a problem for this thread, but thought it might be worth throwing out there too).

I've tried 12.10 drivers, I've tried 13.4 drivers.  Neither make any odds.

I've cleared out all the .ini and config files out of the profile, etc, and re-downloaded a fresh version of cgminer (3.1.1).

I was able to Scrypt mine with the 13.4 miners using Reaper, but in trying to solve the CGMiner issues, now it won't even run.  All the cards ran OK using cgminer in a different machine, but not all at the same time (it was a uATX Celeron machine).

Any ideas?

Eh, that's broken.  A HD7750 is doing 130K here, standard speeds.  Similar to a HD7770.

Try turning intensity down, the HD7750 craps out and crashes the video driver if I run it anything above 15.  15 runs OK, only crashes once or twice a day.  12 is stable 24/7 but only pulls about 110K.

I run it at 15 during the day while I'm at the computer, then 12 during the night when it's unattended.

You'll have to get a network card if the motherboard you're using doesn't have one.  But, I haven't seen a motherboard in about 10 years that hasn't.  You can get USB ethernet cards which are good enough for mining. 

A good price is free.

Fair price for a 5850 is as little as you can, like anything.  Check eBay and see what they're going for.  Use the watch list, so you can see what they sell for.

GPU RAM, doesn't really matter.  Most cards are 1GB at least.  I haven't seen any difference in using a 2GB card over a 1GB one.

I have a HD7770 (Asus), and I also have a HD7750 (Sapphire Low-Profile).  The 7750 was cheaper and gives exactly the same hashrate.  They're pulling about 130KH/s doing LTC. 

Compared to the used HD5870 I got for similar price to the 7750, which is doing 325KH/s, the HD77x0 cards are a bit shit. 

Friends don't let friends use Gigashyte.