Old PSU with new motherboard?

[AC33]

I have an old 400W PSU that I wish to use with new CPU&motherboard for a while.
The PSU only comes with 20pin & 4pin 12V motherboard connectors (SATA and PCIe are not a problem). 12V output is rated 18A (216W).
I need a very basic system with no discrete graphics or multiple hard-drives, and there's a reason for the 2 phase upgrade.
I looked at H55 boards for use with something like the E5700 (65W TDP). They come however with 24pin+4pin.
I also looked at H67 boards with one of the quad cores. They come with 24+8pin sockets, although the manual calls not to forget connecting the "4-pin / 8-pin ATX power plug".

I'm aware that the new specifications call for much more 12V emphasis, and that this is far from ideal, but looking at the review:
http://www.anandtech.com/show/4083/...core-i7-2600k-i5-2500k-core-i3-2100-tested/21
even taking the entire power consumption of even the 2600K seems to be much less than the 18A 12V rating of the PSU. And my system would not be stressed for more than short periods.
I also believe that the 20pin connector can work with the 24pin socket.

So would it? Other then the 12V power, is there a reason for it not to work?
Do you think I can get one or both options to work for a couple of months without crushing?

Thanks in advance for any ideas!

 

[VirtualLarry]

You cannot use an H55 board with an E5700. E5700 is a C2D, Socket LGA 775 CPU. H55 is a socket 1156 chipset.

It is somewhat risky, but as long as you are not going to use a discrete GPU, stick with a single HD and DVD drive, then you probably could get away with using that old PSU for a while. I would replace it with something newer as soon as you can afford it.

Is it a name-brand PSU, or is it a piece of junk no-name unit (that possibly came with a case)? If it's generic, then it may not even be able to live up to its rating. Take that into consideration carefully. Not to mention, the aging that takes place, over the years that you may have had the PSU.

Assuming that the PSU can actually put out 18A sustained on the 12V line, then you should be ok.

I used a ThermalTake TR2-430 430W PSU, which has only 18A on the 12V line, to power my two desktop rigs, when they had E2140 @ 3.0Ghz, and X1950 GT/Pro graphics cards.

 

[PreferLinux]

The 20-pin in a 24-pin plug will be fine. Just make sure it is lined up correctly. I'm not so sure about the 4-pin in the 8-pin plug though. (I've read some things suggesting it won't work properly.) It would work perfectly if the motherboard is designed to accept a 4-pin plug, and that would seem to be the case from what the manual says.

So, yes, it should work fine.

 

[AC33]

Oops, I meant i3 540...

And yes, unfortunately it's generic.

And thanks for replying!