PSU Possible issue with PSU related to VGA

Hello, I've recently purchased a new build and finished setting everything up a few days ago. The build is:

phenom ii x4 955be
4gb ocz platinum RAM
samsung 1tb spinpoint f3 hdd
msi radeon r5850 twin frozr vga 1gb
foxconn 790gx motherboard
ben q 21.5inch hd screen
cic 750watt psu

Now, I've never had trouble assisting my friends before in setting up their builds, but it seems fate has struck me when I've attempted my very own first build.

After installing windows 7 ultimate 64-bit on the system and updating all drivers, I decided to test my new system with a few games. Crysis, just cause 2 and civ v. After playing just cause 2 for an hour or 2 with all working fine I exited the game and tried crysis, but after having played crysis for approximately 5 mins, strange artefacts began appearing all over the screen, little square white boxes is how id best describe them. So I exited crysis and tried civ v and sure enough after about 10mins of gameplay the little artefacts began appearing until spreading across the entire screen. I then decided to re-try just cause 2 and play for a little longer, but there was no need as after a few mins the artefacts appeared yet again. They now appear in every game I've installed but only after several mins of perfectly smooth and playable gameplay.

I've reinstalled all drivers several times, updated windows, overclocked and underclocked the 5850 and to no avail. Luckily my motherboard has onboard graphics as the last time I turned windows on with the 5850 installed I got a blank white/greyish screen and nothing responded. Indeed until now I've been unable to load windows with the 5850 installed, and I can only guess but it actually seemed like the problem was getting progressively worse up until then.

Could anyone possibly assist me with this annoying problem?

One possible thing I have noticed but am not sure if it could make a difference is that my psu comes with only one 6-pin connector, and the r5850 requires 2 6pin connectors, so I've used the one 6pin that came with the psu and used a 6pin to molex that came with the card to connect both to the psu. I'm sure there is ample wattage though and it seems strange that the card works fine until minutes into all of these games...

Any help would be greatly appreciated.

Thanks in advance.

James

I dont know how to upload images to here, so i found an image that looks exactly like mine containing identical artefacts, (i even downloaded unigine to test this and got same artefacts therein).

 

CiC is not a tier 1 psu make. Sounds a bit generic.
If it was cheap then the 750W is probably peak output which would equate to around 550W continuous.

The 5850 needs 35-40 amps on the 12V rail.

 

As dubious as I am about that PSU, it looks like a heat issue possibly the cooler isn't attached properly or the heatpaste/pad isn't doing it's job properly. Could even be faulty video ram.

What are your GPU temps when the artifacting starts to occur?

Power issues usually shut the PC down as soon as there is too much power for the PSU to supply.

Just out of interest what does it say on the side of the PSU in terms of 12v rails?

 

Found a similar post on Tomshardware.
CiC 750W output is
DC Output Max:
+3.3V +5V +12V1 +12V2 -12V +5VSB
*28A * 30A * 20A *20A * 0.3A * 2.5A

 

well depending on how the power is distributed it could cause problems.

If for instance 12v1 is for the MB and CPU (including up to 4.16A for the PCIe slot, measured on this site) and components, and 12v2 is for the graphics then 12v1 could be overloaded, especially if there is up to another 6.25A coming from the molex's to the graphics card.

On the other hand 12v1 could be for everything except the CPU, which 12v2 would handle, and this would be a similar situation. the first 12v rail would have to handle up to 151w (12.58A) just for the graphics card leaving less than 7.5w for the rest of the system, excluding the CPU.

Just for future reference when you're looking to buy another PSU, The Antec Truepower new 650w for example has better power distribution as it has 4 12v rails, each capable of outputting more than (2x22A & 2x25A) each of the cic 750w's 12v rails so long as it doesn't exceed 54A in total (it actually can but efficiency will drop to below the 80+ spec).

The most that could possibly come from 2x20A is obviously 40A, but it's supposedly got 100w more than the Antec.

 

yeah it does sound like it's overheating.. but to eliminate it's power, try unplugging that 6 pin converter and making sure the two 4 pin molex connectors are plugged into separate connects going back to the psu, preferably ones with the least amount of devices

you might be pulling that 75 watts through an overloaded rail, and your psu is failing.. I've seen this with an antec earthwatts 450 once.. after it could run sli 9800's no problem

I like single rail.. I know guys swear on multi rail for overclocking stability but I've never had a problem