Totally perplesed

The usual trouble shooting. Running memtest86, ruinning 1 stick of ram at a time, removing any overclock, doing a cmos reset (check manual), if memtest is ok, trying different ram voltages (1.5V -> 1.65V), timings (9-9-9-24, increasing to 11-11-11-28, 1T/1N, or 2T/2N), using the memory XMP profile if your motherboard supports it (check manual, should be in BIOS ram settings).
 
The motherboard is using the case stand-offs right? Nothing's touching the case that ought not be?
 
Might have the solution?

Ok guys, been doing research and I need any opinion & suggestions.

I now suspect my PSU isn't providing enough power on the 12v rail. The PSU is an Akasa PowerMax 850w:

http://www.bit-tech.net/custompc/reviews/129287/akasa-powermax-850w.html

AS stated, GPU is Asus Radeon 6850.

I've now discovered that the Radeon needs a minimum of 500w power supply with at least a 40A 12v rail and 2x6pin power connectors. Problem is, the Akasa site above says that the 12v rail works as follows:

"Each of these 12V rails is rated as being capable of supplying up to 35A, and they distribute their load as follows: 12V1 powers the motherboard, half of the CPU, two of the PCI-E cables and the Molex ports, while 12V2 powers the other half of the CPU, the other two PCI-E cables and the S-ATA ports"

So, am I correct in thinking that the reason the PC won't boot is because there's not enough power going to the 6850? Assuming that's the case, can anyone recommend me a reasonably priced PSU that will do 40a 12v rail. It doesn't have to be 850w, as long as it does what I need!

All opinions/advice gratefully accepted.

Rob
 
First off the Radeon doesn't need 500w.. That's a complete system requirement if using Radeon.

Power the GPU with 12C2, the rail that powers S-ATA cables.
 
check PSU manual. It will tell you which rails are which.. ususally a black strip on one of the main wires so you can tell one rail from the other.
 
Looking @ manual, but not ure what you mean. Sorry, not very good w this aspect of PCs, but really appreciate yr help.

This is the manual online:

http://akasa.co.uk/update.php?tpl=p...supplies&type_sub=Performance&model=AK-P085FG

What should I be looking for?

Having read a bit, I think that although the 2 12v rails can go to a quoted 64a, the power is being shared between various components, which leaves the GPU short of juice, meaning the pc won't boot?
 
Application 850W PC Power Supply
Designed for AMD / INTEL based systems
ATI / NVIDIA graphics
Form factor ATX12V 2.2 & EPS12V 2.92
Dimension 150 x 160 x 86mm
Typical efficiency 85.49% (80.89% at full load)
Power factor correction Active PFC
Fan 135 x 135 x 25mm, dual ball bearing, 600-1800RPM
Motherboard connectors 1 (20+4pin)
ATX12V connectors 1 (4+4pin)
8/6-pin PCIe 2 (6+2pin)
PCIe 6pin connectors 2
SATA connectors 6
Molex 4pin connectors 6
FDD 4pin connectors 2
Cables finish Black mesh (all cables, full length)
AC power input Full range 100V to 240V (auto switching)
Protection Over Power / Voltage / Current / Temperature
Short Circuit
Safety UL, TUV, CE, FCC, CB, N, D, FI, S
Product code AK-P085FG-BKUK (UK)
AK-P085FG-BKEU (Europe)

PowerMax 850W Output Specification
Rail +3.3V +5V +12V1 +12V2 -12V +5Vsb
Maximum Wattage 180W 768W 3.6W 15W
Maximum Load 25.0A 30.0A 35.0A 35.0A 0.3A 3.0A
64A

The manual doesn't give much more info than this
 
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Try looking at the wires coming out of psu into the S-ATA and Molex cables. Each one of them is on a different 12v rail and the 12v wires on one should have an extra color line or dashed line or something making it look a little different.

Most new PSU are single rail so you don't need to worry about this kind of thing.
 
Multi-rail was originally done to limit the total power on each rail for safety. It's all fine and good until you need to sort out what cables are on what rail... as you know now only too well. ;)
 
doyll said:
Multi-rail was originally done to limit the total power on each rail for safety. It's all fine and good until you need to sort out what cables are on what rail... as you know now only too well. ;)
Click to expand...

Yep, I'm totally baffled lol. There don't seem to be that many dual rail PSU's about any more.
 
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