there are pros and cons to each.

multi rail: Pro - overcurrent protection on each rail. a short on one string (rail) will shut the PSU down before the string wiring can catch fire.

multi rail: Cons - have to balance the rails

single rail: Pros - no load balance worries. jump start your jeep!

single rail: Cons - fire if something shorts big time.. 100 amps on a single wire = bad news.

BTW internally most all "multi rail" PSUs have one 12v source (which also powers 3.3v and 5v rails), each rail has  overcurrent protection though.

some 6870s are $160ish at the egg (after rebate) and can pull just north of 300 Mhash @ 1000 core.

definitely no.

earliest ATI that can mine are HD 4xxx cards, and even my 4850 isnt worth folding on (80 M/hash@120 watts or so). unsure on nvidia, but you dont mine with nvidia unless you have free electric anyway.

but those cards rock for mame and Ye Olde Dos Box games.

the PSU manual may specify what strings are on what rail.

for example my antec TP 550 new manual (pdf link) tells exactly whats on what.

without pics of the card minus the HSF assembly its hard to tell, but I would be worried about the VRMs not getting airflow. they are typically near the PCIe power connectors and that path is what it sounds like you are blocking.

can you monitor VRM temps?

seems the bulk are in the same boat Ill soon be in.. casual miners @ 1 to 5 gigs (Im at 900 mhash currently). most of my rigs serve double duty: mining (or folding) plus something else.

I had 2 systems that were already in use 24/7 and due for video card upgrades anyway, so I just went with slightly higher horsepower ATI cards than I was originally going to go with. 6870 for the day to day rig, 6770 for the HTPC. dropped a 5830 into an old P4 rig thats a dedicated miner and may add the old 4850 (was in the day to day rig) into it when I get my PCIe cable extensions and my antec 550 treo RMA come back. 4850s are just profitable enough ATM (for me) to add it in and it should just about give me 1 ghash total.

to add more power I would need another box. but Im planning to build a storage box with server 2008 anyway (planning to move to centralized NAS for ease of backups, 3 terabytes spread across 5 rigs is a pain to backup individually), so I would go with a mobo with a lot of PCIe slots. move the 5830 and whatever into that.

for me mining is just a way to help finance more toys and help with folding costs

had two fans die in my years of folding with 24/7 100% fan speeds: ATI HD4850 (reference design) and HD3870 (zerotherm HSF). took like 3 years of non stop 100% fan speed to kill them. other cards Ive had have run years at 100% with no issues.

my personal opinion is dont worry about it, aftermarket coolers are fairly cheap. BUT case fans are cheaper still, no brainer easy to replace, and allow a reduction in GPU fan speed for the same temps. HOWEVER its a good idea to keep the card fans at 60% (or so) minimum as the cards memory and VRMs depend pretty much solely on airflow from the GPU fan.

running the memory with no sinks is probably OK IF you underclock the memory (best way is in the BIOS) but you MUST have heatsinks on the VRMs.  they WILL cook themselves with no sink.

random lockups and BSODS. boot failures on initial cold boot requiring several restarts to finally boot stable.

if you can run furmark (on all GPUs) and prime95 at the same time for an hour your PSU and system cooling are fine as that will be max power draw. *** CAUTION *** you aint seen temps till youve dont that so BE AWARE you can possibly damage your PSU, GPUs, and/or CPU if youre not careful monitoring temps on GPU and CPU during the test. *** CAUTION ***

game and HTPC computers: audio card. miners/folder/general purpose rigs: nothing.

at 80% efficiency, yes.

power supplies have "sweet spots" on their efficiency curve, the manufacturer should have a chart. one may peak at 50-80 % load, another at 75-85% load. they vary. but 80+ certified means it will never be below 80% no matter what the load.

you need to reboot for BIOS changes to take effect. shut off legacy usb (if your not using it) coms, printer, sound, raid, all that. probably save only a couple watts if that though.

tried underclocking the PCIe bus? how about undervolting other chips (southbridge?). this last depends on your bios/chipset. Im not up on AMD stuff, so I may not have the right term.

true, that soldering irons are your friend. and a molex pin extractor (DIY or bought) is a wonderful thing too, heh.

CPU wise it would be fine but power supply might be an issue. ATX 1.x supplies (20 pin mobo connector, and what was used during the socket a era) were light on 12v rails. check your rigs current PSU.

ATX 2.x (24 pin mobo connector) had beefier 12v rails as thats when mobos switched to deriving most voltages from it. ATX 2.x is backwards compatible so you could get a ATX 2.x PSU, drop it in if need be and later put it into a newer build.


your cables extenders would need molex connectors to get the 75 watts that the pcie spec calls for, doubt a pci slot will give that. dunno if the pci to pcie adapter takes that into account, so watch out for it.

from what Ive been reading (I only run windows atm as I have the extra licenses) it makes no difference. win7, vista, xp, *nix are all pretty much the same m/hash wise on the same hardware. what is different is ease of use as win has tons of overclocking and over/under volting tools. *nix, not so much.

the big variables for m/hash production are the core/mem clocks, miner (and its flags), SDK version and CAT version used. each OS/card combo seems to like a different combination to find its sweet spot.

making sure the PSU is drawing fresh (ie not heated from the cards) air may help the PSU efficiency. Im unsure but I do know the hotter they get the less power they can deliver. whether cooler = slightly better efficiency is true or not I dunno but even 1 or 2 % = 3-6 watts on your setup. 

and man, 300 watts that whole system on those two cards? sweet! I pull 300 watts from the wall on a P4 prescott/single 5830 rig. no DVD, other cards, one HD.  Ill have to try undervolting the 5830. cant mess with CPU/mem stuff as that rig is a HP/Compaq business computer work gave me when they retired it. no BIOS options for the good stuff. that thing sat for ages in the basement, never thought Id would actually use it lol.

as a long time folder, starting with a coppermine p3 1.0 years back and now folding with 2 GTX 285s and a Q9650 @ 3.8, Ive always liked the hardware aspect.

so, what hardware did you folks start with back in the day?

as for me a couple month ago i saw bitcoins threads at various hardware sits and pretty much blew it off. like, riiiight.. money from video cards.. as time passed and more threads kept coming up, I started to seriously look into it. at that point I switched my HD4850 (which sucked a folding anyway, but hey science is science) and signed up at the various sites to get the money into a bank account to see if it actually worked. well of course it does.

so.. hardware..

started with the 4850 but soon upgraded to a 6870 in the day to day rig. then replace the HD3850 in the HTPC (it sucked at HTPC duties, no real 23.97 FPS support) with a 6770. HDMI 1.4a!  3D support! 23.97 support! yea!. those pull double duty in the respective rigs  where I can easily justified as legit hardware upgrades. but then..  then a 5830 in an old P4 prescott carcass as a dedicated rig in the basement.

guess the bug has bit. 800-850 M/Hash total. fun,  I know its not gonna make me rich but its more hardware to play with and I can fold with it later if I want.

anyone else want to tell their hardware story?

my sapphire 5830 pulls 300 m/h at 960/354 stock volts (guiminer on xp32 2.1 SDK / 11.6 driver.  -f 15 -v -w 256 flags. havent tried higher clocks as its on a Delta 340 watt PSU, waiting for my Antec 550 trio RMA to come back. then Ill put the screws down.

there are many "sweet spots" - different work sizes and mem clocks can make a decent difference (10-15% maybe).

you can up the f number while gaming but when youre not set to -f 1 or -f 15 or something. your hash rate will thank you.

for my HTPC for instance i run it at f 1 at night (dont care about screen lag), f 30 during the day (so my wife can watch stuff) and its off completely when watching a blu ray rip as I want perfect output.

higher f number = less hash rate. if 24/7 mining it adds up.

thats a kingwin psu. I wouldnt trust its specs. if it were corsair, psp&c, seasonic, antec I would say its good as they are real world rated (actually underrated in most cases).