Interesting. Which Sapphires are you using? The 2L's or 4L's? What is your core voltage set at? Also how close together are your GPUs to each other?

I also have an identical spare motherboard I have tried my equipment in with the same result. I have also run just two cards in each board again with the same results.

Appreciate the feedback and would like to know exactly how much power you're using when you do find out.

I'm running a rig with 4 7950's. The amount of power its drawing is enormous. I have a 1600w PSU and im pulling around 1500 watts. I have spent weeks trying countless settings and under clocking via, AfterBurner, Trixx and through the cgminer.conf alone. All yield the same results. What it seems to boil down to is no matter what settings im using the higher hash rates I get on my cards the hotter they run and more power they use. It makes sense to me and this also seems to be indicated in the SCRYPT README included with cgminer. I've seemed to find my GPU's sweet spots for my system but the amount of power its drawing is concerning.

Let me start with my hardware:

Rig Hardware
GPUs: 4 x SAPPHIRE|100352-4L HD7950
CPU: AMD Athlon II X2 270 Regor 3.4 GHz 2x1 MB L2 Cache Socket AM3 65W Dual-Core Desktop
Motherboard: MSI AM3 USB 3.0 + SATA 6Gb/s AMD 890FX Chipset Motherboard 890FXA-GD70
Memory: Corsair XMS3 16 GB (4 x 4GB) 1333 MHz PC3-10666 240-Pin DDR3 Memory Kit CMX8GX3M2A1333C9
PSU: 1 x COOLMAX ZPS-1600B (14642) 1600W ATX12V v2.31 & EPS12V v2.92 SLI Ready CrossFire Ready 80 PLUS SILVER Certified Modular
Case: COOLMAST HAFXB LAN BOX CASE

OS: Windows 7 x64 Bit

GPU Running Info: Catalyst 13.5 Beta Drivers
GPU 0: Temp 79, 600Kh, I: 19
GPU 1: Temp 78, 650Kh, I: 20
GPU 2: Temp 81, 590Kh, I: 19
GPU 3: Temp 76, 665Kh, I: 20

CGMiner 3.0.0 - CGminer.conf
"intensity" : "19,20,19,20",
"worksize" : "256,256,256,256",
"kernel" : "scrypt,scrypt,scrypt,scrypt",
"lookup-gap" : "2,2,2,2",
"thread-concurrency" : "21000,21000,21000,21000",
"shaders" : "1792,1792,1792,1792",
"gpu-engine" : "1000,1125,1000,1125",
"gpu-fan" : "0-100,0-90,0-100,0-75",
"gpu-memclock" : "1550,1699,1525,1699",
"gpu-memdiff" : "0,0,0,0",
"gpu-powertune" : "0,0,0,0",
"gpu-vddc" : "1.069,1.069,1.069,1.069",
"auto-fan" : true,
"auto-gpu" : true,
"temp-cutoff" : "85,85,85,85",
"temp-overheat" : "83,83,83,83",
"temp-target" : "78,76,79,75",
"api-port" : "4028",
"expiry" : "0",
"gpu-dyninterval" : "7",
"gpu-platform" : "0",
"gpu-threads" : "1",
"hotplug" : "5",
"log" : "5",
"no-pool-disable" : true,
"queue" : "1",
"scan-time" : "60",
"scrypt" : true,
"temp-hysteresis" : "3",
"shares" : "0",
"kernel-path" : "/usr/local/bin"

I've had people tell me they were able to achieve much lower temps with the same hash rates with the same hardware. By the end the conversation I would only find out the hardware they were using was not the same. I've also had people point out the obvious such as sufficient cooling. I have the room temp at 72F and very good airflow on the cards.

Things I have not tried yet. I have not used riser cables. I have not tried to set my 16x slots to 8x which I have been told to do. Honestly not quite sure how to do that. If anyone is running a rig with this hardware or have some other useful advice it would be appreciated. I'm just trying to figure out if anyone is obtaining these kind of hash rates (with the same 7950's) as I am @ lower temps or wattage. I can obtain lower temps and power consumption but always at the cost of hash rates.