New computer won't boot anything

[Aisling]

We just built a new computer. We're pretty sure everything's plugged in properly, and the power supply should be enough, but when we try to turn it on we get nothing. The power light turns on, sometimes the drives spin up... but there's no BIOS, and sometimes the drives don't spin up. And sometimes the power light turns off for a second or two before turning back on.

I suspect this is a power supply problem. But we don't have any spare power supplies we can swap in to test the theory. What else can we try?

Specs:
Intel Core i5-3450 3.10 GHz LGA1155 CPU
Gigabyte Intel Z77 CrossfireX ATX MB
(4) CRUCIAL 4GB DDR3 1333 MT/S (PC3-10600)
Seagate ST2000DM001 Barracuda 7200RPM 2 TB SATA 6 GB/s NCQ 64 MB Cache 3.5-Inch Internal Bare Drive
LG 12x Internal Blu Ray Combo OEM
Samsung 22X DVDRW SATA OEM
EVGA GeForce GTX 650 1024MB GDDR5 DVI mHDMI Graphics Card 01G-P4-2650-KR
Sabrent 6-CH 5.1 Surround Sound 3d PCI Sound Card
Ultra 8 Port USB 2.0/Firewire Combo PCI Card
Diablotek DA Series 500w ATX Power Supply
Thermaltake V9 Black Editon ATX Blk Mid-T Case

ETA: We're probably going to have to bring it to a shop on Monday, I know. I'm holding out hope that we can avoid spending $75 bucks plus however much they overcharge for the power supply.

Edit 2: We decided to try turning it on again, because, well, I've got weird luck. We got a flash of a BIOS screen, and then it asked for a boot device. So we put in the disc for Windows 7, and now... black screen. Super frustrating.

Edit 3: We got into BIOS, for a little bit. We couldn't get Windows to install though. We tried rebooting, and now BIOS won't load either.

[sms001]

Erratic starts before the OS can be one or several of many things. If it was the initial boots of a machine I'd assembled myself, the first thing I'd check would be that the motherboard was mounted properly - completely isolated from the case. Next would be memory (Try each stick separately in slot 1), then the PS you've already suspected. Power button leads and power supply connectors are also leading culprits.

Good luck!

[Aisling]

How would you name sure the motherboard is isolated? The case has these weird raised bumps around the screw holes. Are we supposed to use the hex screws on top of them? The motherboard will be sitting really far out if we do...

[Aisling]

SUCCESS! We took all but 1 memory stick out, and now, we've got Windows installing! Thanks SOOOO much sms! How can we thank you?

Edit: nevermind... now it's black screened during an installation reboot.

[TheSHAD0W]

I was going to ask if you had a speaker hooked to the motherboard. The BIOS will often beep the speaker if it encounters a problem as it initializes.

[Aisling]

No speakers hooked up right now, no.

[Aisling]

New observation: trying to reboot or turn it on again very soon after shutting down causes problems. But if we let the computer sit for a few minutes, it'll boot up. (We got Windows installed, btw.)

If it's an isolation problem, we don't want to use the hex screws because that would mess up the location of some of the plugs in the back (plus they don't actually fit in the case anyway). Would rubber washers work?

[emax4]

The GTX and high-end graphics cards always need a plug from the power supply connected to them, whereas other simply use power from the PCI-express slot. I recall having a Radeon HD6770 and having a similar issue. Have you ensured that not only is a plug from the power supply going to the card, but that you have enough juice from the PS to the card? Power supplies are listed by the maximum output and not normal output, so it's essential that you have a higher wattage power supply than what is required.

[Aisling]

We do have power going to the video card, yes. And we're pretty sure the power supply is more than necessary... assuming the website used was accurate. At one point we took out the video card and that didn't fix anything.

We estimated needing about 400 watts, and got a 500. Is that not enough spare? And what website would be good for providing the necessary info to decide?

[Chromatix]

The CPU and GPU are not especially high-end, so a 500W PSU should be sufficient, if it has the right connectors and they are all plugged in correctly. Make sure of that last point - some of them will be pretty stiff. Most systems require a 24-pin main connector (usually made of a 20 and a 4 locked together), a 4-pin ATX12 connector which might be on the opposite side of the board from the main one, and a 6-pin PEG connector on the graphics card - if there isn't one there, just leave it off.

What concerns me however is that Diablotek is not a PSU brand that I recognise - which is a huge red flag. The name sounds like it was chosen to appeal to gamers who don't know any better, rather than to techies and enthusiasts who do.

A really good way to tell the difference between a good PSU and a bad one is to look for "80 Plus" certification - it's meant to measure efficiency, but in order to certify it, they have to actually run the PSU at full power on a calibrated instrument, at which point most truly subpar PSUs will simply blow up. An 80 Plus certificate therefore means that it did *not* blow up.

Of course, even a good PSU brand can have individual examples that just don't work. Since this is the prime candidate, I suggest taking it to be tested or exchanged.

It sounds as though you *have* fitted the m/board correctly, since the ports are properly aligned with the openings. The extra hex-shaped standoffs are to use with large m/boards which require extra support at the edges, using threaded holes that are not raised off the backplate. This is a good thing, because a short-circuit would almost certainly have ruined something.

A useful test would be to disconnect all of the drives and external peripherals, leaving only the CPU, heatsink, minimal RAM, the GPU and the monitor attached, then power it up. If it is more stable like that than you have described so far (you should be able to go into the BIOS and look at the temperature and voltage readouts, which are also useful) that's a good sign that the PSU is struggling. In this case you should probably ask for a different brand of PSU rather than a replacement of the same brand.

[Aisling]

We're sure everything's plugged in snug, and correctly. We're always very careful on that point. And we did unplug the "extras" one time to see if things would boot. It didn't really seem to help.

I don't see anything on the box or in the booklet for the PSU about any certifications. So that's probably a bad sign.

What's a good brand for a PSU? This is only our second build, and we really don't know much about brands. Mostly we just look for things with decent ratings on TigerDirect and Amazon. Buying a new PSU shouldn't be too hard, and it wouldn't be the first one we've switched out.

I'm glad to hear the raised screw holes in the case aren't the problem. This case, oh gods, it's such a pain in the butt. We've had the hardest time getting things in. I only bought it because it was on sale, and has USB plugs on the top instead of at the bottom which is much more convenient for us.

[emax4]

Corsair is a good brand that I've used. If you'd like a specialized store, check out NewEgg.com, as they have a more plentiful selection and manufacturer rebates on mostly everything.

[Aisling]

Thanks emax.

[Aisling]

I'm considering the Corsair Builder Series CX 600 watt. The case has a lot of fans in it. One small in the front and two big ones. I think it's meant for people who push their computers a lot harder than we do. It's a lot more money, but clearly necessary. Unless people think a 500 would be enough? I wanted to get a 550 but the only one I can find is even more than the 600 watt... confusing.

[Chromatix]

Corsair is a trustworthy brand who make several types of PC components, and their CX series PSUs are all 80 Plus certified. They should have a 500W version as well as the 600W one you found, so it's worth comparing the prices. The 600W size isn't oversized though, so there's no actual disadvantage to taking it.