Problems across desktops

[possiblyreef]

I have 2 pc's with possible transferable problems

PC1:
Around oct last year i was getting a CPUboot led on the motherboard, this would cause the pc to stall on boot for a few mins then rectify itself and work fine. Eventually it wouldnt boot at all. I bought a new AM3+ motherboard on the off chance it might work, it didnt so was going to RMA the cpu.

PC2:
my gf's pc. Just before christmas she said it made a screeching noise whilst i was out, she said it booted fine, turned it off and when i went to turn it on, nothing. i transfered my pc1 psu to hers, it started up but no display and the cpu fan was revving up and slowing down.

i ordered her another cpu (phenom ii 965) as id had the one in there for about 4 years. tried it out last night using.
new cpu
pc1 psu
pc1 new motherboard
both graphics card (pc1/pc2 560ti/gtx460 respectively)

any ideas on what to try next, im against paying a few hundred £ for a hardware diagnosis as at this point i have most of a new build.
Should be able to try a friends gpu later on, could a faulty psu from pc1 cause both of these problems

 

[possiblyreef]

if it helps, cant remember everything as im at work and cant check now:

PC1:
amd fx-8150 bulldozer
mobo- asus (cant remember exact model but was around £80) am3+
twin frozr 560ti
8gb corsair vengance
OCZ stealth xtreme 600w

PC2:
amd phenom ii 965
mobo - again asus but this time am2+
gainward gtx460
8gb gskill ripjaw
offbrand psu 600w (think it was atleast 48a across dual rails as i needed a pcie connector)