8pin CPU power on motherboard but 4 pin on PSU

[geeky]

I've just replaced some parts of my PC. Upgraded to a P8Z68-V Pro/Gen3 motherboard, 3570k & 8GB Corsair Vengeance LP 1600Mhz DDR3.

I've noticed the motherboard only has an 8 pin socket to supply CPU power (my old board had a 4 pin). However my Corsair HX 520W psu only supplies a 4 pin for CPU power.

I can't really afford another PSU right now due to the cost of the components above. Can I use the 4 pin into the 8 pin socket and leave 4 pins empty? Is it safe to do this? Technically, whats the difference between them?

Thanks.

 

[cin19]

If you want go to get this " 4-Pin Male to 8-Pin Female Power Cable M-F " http://www.amazon.com/Male-Female-Power-Cable-Adapter/dp/B005L90Q0O

The high end MB need more power like for OC so they need the 8-pin connect. But your PSU should be fine for your system and I think your PSU should have other 8-pin cup 12v connector. Usually only the low power PUS has the single 4-pin 12v connector.

 

[alexoiu]

If not OC-ing, you can connect the 4 pin to the 8-pin onboard header.

 

[geeky]

Thanks all.

Cin I opened up the case and rechecked and the psu does indeed have a separate 8 pin cable. I'd forgot that I'd hidden it away with my cable management when I originally built it.

When I did the upgrade I checked my bag of leads that came with the PSU and thought it didn't come with the 8 pin as there wasn't one in the bag (modular psu).

However the 8pin is one of the main cables that isn't modular.

I've disconnected the 4 pin now (and hidden it away) and attached the 8 pin, for what its worth.

 

[TheKLF99]

I've been wondering the same thing. I've built a number of PC's now with this, the first one I came across was someone who'd built their own PC, had it running with just 4-pins, got a convertor for it, and ever since they added the convertor the PC stopped booting, so they called me out to take a look at it. I removed the connector, re-plugged the 4-pin connector back in and it started working again fine (why they didn't do that themselves is beyond me?).

I then built a few computers with this on, the first one I came across whilst actually building a new PC had a plastic cover over the extra 4 pins. I've built numerous ones with just the 4-pin connector on and no 8-pin.

Also the PSU's I get always seem to come with 4-pin cables anyway - I always try and use 750w PSU's regardless of whether or not it's overkill for the PC I'm making (I'd rather the person have more power there, especially when they start plugging things into the USB ports like sat-navs, and mobile phones, and external hard drives and forget how much extra power all these things are pulling from the main PSU!) - also a lower wattage PSU might be running at it's limit and burn out faster (like trying to drive a car all the time at it's top engine speed!). I had one person I went to and I couldn't believe how much they'd got running off a 300w PSU and wondered why it had gone - 2 internal hard drives, 2 DVD drives, and 4 external hard drives, USB ADSL modem, mobile phone charging, and sat nav charging (as well as the PC!!).

But even though I'm using such high powered PSU's I've never once yet come across an 8-pin connector on any of them, they all have the 4-pin and the 6-pin PCI-E connectors, but as of yet no 8-pin. I presume it's because I never use the modular PSU's, but all the PC's I build with a 4-pin connector in the 8-pin slot all work - so if it ain't broke why fix it? It is strange though how there is never any mention of this in the manuals (if you look at the pin layout in the manual though you can kind of figure it out, but it's not very clear).

 

[dmanbluesfreak]

I've been wondering the same thing. I've built a number of PC's now with this, the first one I came across was someone who'd built their own PC, had it running with just 4-pins, got a convertor for it, and ever since they added the convertor the PC stopped booting, so they called me out to take a look at it. I removed the connector, re-plugged the 4-pin connector back in and it started working again fine (why they didn't do that themselves is beyond me?).

I then built a few computers with this on, the first one I came across whilst actually building a new PC had a plastic cover over the extra 4 pins. I've built numerous ones with just the 4-pin connector on and no 8-pin.

Also the PSU's I get always seem to come with 4-pin cables anyway - I always try and use 750w PSU's regardless of whether or not it's overkill for the PC I'm making (I'd rather the person have more power there, especially when they start plugging things into the USB ports like sat-navs, and mobile phones, and external hard drives and forget how much extra power all these things are pulling from the main PSU!) - also a lower wattage PSU might be running at it's limit and burn out faster (like trying to drive a car all the time at it's top engine speed!). I had one person I went to and I couldn't believe how much they'd got running off a 300w PSU and wondered why it had gone - 2 internal hard drives, 2 DVD drives, and 4 external hard drives, USB ADSL modem, mobile phone charging, and sat nav charging (as well as the PC!!).

But even though I'm using such high powered PSU's I've never once yet come across an 8-pin connector on any of them, they all have the 4-pin and the 6-pin PCI-E connectors, but as of yet no 8-pin. I presume it's because I never use the modular PSU's, but all the PC's I build with a 4-pin connector in the 8-pin slot all work - so if it ain't broke why fix it? It is strange though how there is never any mention of this in the manuals (if you look at the pin layout in the manual though you can kind of figure it out, but it's not very clear).

I ran into this issue too. I replaced my old microATX motherboard with an EVGA 680i (used, but witnessed working). The 8-pin connector on my PSU (it's actually a 6 pin with a piggyback of 2 extra pins) plugged into the motherboard's CPU 8-pin slot kept my computer from booting. I normally use the 8 pin connector on my graphics card, along with another 6 pin (GTX280) but since I'm replacing the motherboard, I tried booting it without the graphics card installed to see if the 8-pin was indeed required - thus, I tried the 8-pin since it was the proper shape for the motherboard. I find it odd that the 8-pin doesn't work and the 4-pin does, but I guess if it's not broken, don't fix it.

Any idea why the 4 pin would work and the 8 pin wouldnt? I didn't think twice about it until I read your post about it happening to someone else. I'm not worried about power draw since I don't plan on overclocking my Q6600.

 

[norsestar]

The 4-pin CPU power connector works and the 8-pin (6+2-pin) doesn't because the 8-pin is a PCIe power connector, not CPU. The two connectors are wired differently, so plugging a PCIe power plug into the CPU power socket shorts +12V to ground and shuts down the PSU.