I recently bought a new gfx card and a psu to go with it. Annoyingly it's turned out that the card needs 'two 75W 6pin PCI express power connecters'. My PSU (after everything else is hooked up) only has one to spare.

Is there an adaptor to split this into two I can buy or am I screwed?

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Original post by JamesPenny I recently bought a new gfx card and a psu to go with it. Annoyingly it's turned out that the card needs 'two 75W 6pin PCI express power connecters'. My PSU (after everything else is hooked up) only has one to spare. Is there an adaptor to split this into two I can buy or am I screwed?

Each adapter is designed to provide a specific amount of power, in your case 75W/5V (=15 amps).

What do you suppose would happen when your video card attempted to draw 30 amps from the transformer providing 15 amps?

You should replace the power supply, or read your video card manual to see if both connections are required.

There are 4pin Molex to 6pin PCIe adapters. Not sure how well they work.

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Original post by Yann L There are 4pin Molex to 6pin PCIe adapters. Not sure how well they work.

If your PSU's molex rail isn't rated for enough current (i.e. enough amps), this is a surefire recipe for a blown fuse at best and a small house fire at worst.

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Original post by ApochPiQ If your PSU's molex rail isn't rated for enough current (i.e. enough amps), this is a surefire recipe for a blown fuse at best and a small house fire at worst.

Very unlikely. A 6pin PCIe connector is max rated at 75W. Split onto two rails, each Molex connector would need to supply about 38W. Considering that a single DVD writer (the type of hardware that is/was supposed to go on the Molex) can draw up to 30W alone, your house certainly won't burn down when trying this.

It may however affect stability, depending on how the voltage regulation is done on the OPs PSU (ie. if it has separate regulators for the PCIe and Molex rails, and how the regulators on the Molex rail respond to the highly variable current usage profile of a graphics card).

OK, OK, so I was a little melodramatic [grin]


In Ye Olden Days, PSUs were considerably less fault-tolerant. Over-drawing a rail was known to at the very least blow up the fuse in the PSU itself, and for some of the cheaper, more hazardous units, cause actual catastrophic circuit failure. Although I've only over-drawn and (literally) exploded one PSU in my own personal experience, I don't doubt that the shitty units we used to be plagued with in Asia would be happy to start a small fire if overloaded.

That said... it's 2010. Don't buy crappy off-brand PSUs, and the worst you're likely to run into is a very unstable system.

I'll give a bit more info, it was late when I typed the OP and it aint too clear.

I've got an ACER Aspire M3800 with all the stock parts. The gfx card is shit and overheats all the time* so I've bought a fancy new Radeon HD 5830** and a 550W PSU*** to run it.

However the card needs two two 75W 6pin PCI express power connecters and I don't have any to spare coming out of the PSU. I do however have a molex spare and the card came with two 6pin PCI to molex adaptors. So I plugged that in to the card and got the fan turning etc but there was no visual output. Windows had booted because I could use keyboard commands to shut down the PC.

I then tried unplugging the DVD drive and giving the card two molexes etc but still no joy. To me this implies something else is the problem (although not having a drive and gfx card at the same time would make playing games awkward).

Is it possible the motherboard doesnt like the card? If so, how much would it cost to get a new motherboard etc?

Thanks for helping.

*I currently use a cooling system of my own design: Take the side off and slap a desktop fan next to it.

**It was on sale and I didn't realise how good the 5850 was in comparison for the price.

*** It's from some people called WinPower and it cost £20. Should I evacuate the area?

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Original post by JamesPenny I'll give a bit more info, it was late when I typed the OP and it aint too clear. I've got an ACER Aspire M3800 with all the stock parts. The gfx card is shit and overheats all the time* so I've bought a fancy new Radeon HD 5830** and a 550W PSU*** to run it. However the card needs two two 75W 6pin PCI express power connecters and I don't have any to spare coming out of the PSU. I do however have a molex spare and the card came with two 6pin PCI to molex adaptors. So I plugged that in to the card and got the fan turning etc but there was no visual output. Windows had booted because I could use keyboard commands to shut down the PC. I then tried unplugging the DVD drive and giving the card two molexes etc but still no joy. To me this implies something else is the problem (although not having a drive and gfx card at the same time would make playing games awkward). Is it possible the motherboard doesnt like the card? If so, how much would it cost to get a new motherboard etc? Thanks for helping. *I currently use a cooling system of my own design: Take the side off and slap a desktop fan next to it. **It was on sale and I didn't realise how good the 5850 was in comparison for the price. *** It's from some people called WinPower and it cost £20. Should I evacuate the area?

No idea about your PSU (you should have amps and power rating stamped somewhere on the side), but as a general rule of thumb, I'd consider a Corsair CX500 / CX600 to be the minimum required PSU for a gaming rig (meaning, with a dedicated 2x6 pin graphics card or more). Antec TruePower 650W, Seasonic S12, modular Corsairs also a good investment.

So IDK, maybe your PSU not working, maybe your video card fried...

Some motherboards give you the option to disable PCIE/AGP video support in the bios. Unplug the card, go into the bios(assuming your motherboard has built in video), and make sure this isn't set. You also may be able to disable onboard video too. Try this also and if it doesn't work reset the bios with the jumpers on your motherboard.