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 Post subject: Low power causing problems booting?
PostPosted: Tue Jun 07, 2011 12:45 pm 
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Joined: Sat May 21, 2011 8:16 am
Posts: 8
Hi all, I've just bought a new PC and got to the fun part of building it tonight. Only, it didn't end up being fun. For some reason it won't do anything with the new graphics card in and a keyboard connected...

Ok, specs:

Antec nsk2480 - 380w 80+ bronze PSU
i3-2100t
Asus P8-H67-M LE
4gb ram
Sapphire HD 5670

At this point, I've connected no hard drive up as I just want to get it to bios. I've not got any case fans running, no CD drive nothing.

If I take the graphics card out, it seems to happily boot and get to bios using the on board HDMI.

Interestingly, it will boot if I disconnect the usb keyboard, it gets stuck in a cycle of rebooting because there's no keyboard but at least I can see the POST screen come up. If i put the keyboard back in, it will get in a cycle of rebooting but I'll never see anything apart from maybe a white bar at the top of the screen.

Can this really be a lack of power? 380w for a 35w TDP processor, a motherboard and a graphics card that is powered purely by the motherboard. I tried dropping it down to 2gb ram but it's the same as before. It gets to POST without the keyboard, put the keyboard in and it doesn't display anything?!?!

Thanks for any info on this

Lewis


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 Post subject: Re: Low power causing problems booting?
PostPosted: Tue Jun 07, 2011 8:17 pm 
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Joined: Wed Feb 04, 2004 2:12 am
Posts: 2831
Location: USA
I am not sure that I follow the sequence of events you described correctly, but I am fairly sure you have enough PSU power. One potential thing to investigate is that, unless you disable the fan speed check in the bios, many systems will not boot up if the CPU fan is not running (with a certain minimum RPM verified by the bios that requires the fan be attached to CPU header on mb).


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 Post subject: Re: Low power causing problems booting?
PostPosted: Wed Jun 08, 2011 12:36 am 
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Joined: Sat May 21, 2011 8:16 am
Posts: 8
Ok I'll try and explain a little better. To eliminate questions about power, i've disconnected the HDD and the case fans. Note the CPU fan is still on and running.

Scenario 1:
Motherboard + CPU + 4GB DDR3 + Onboard HDMI output to TV + mouse + keyboard = Happily boots to bios

Scenario 2:
Motherboard + CPU + 4GB DDR3 + Onboard HDMI output to TV = Happily boots but says no keyboard attached and so keeps rebooting itself

Scenario 3:
Motherboard + CPU + 4GB DDR3 + Sapphire 5670 with HDMI to TV + mouse + keyboard = shows nothing on screen apart from maybe a white bar at the top, keeps rebooting

Scenario 4:
Motherboard + CPU + 4GB DDR3 + Sapphire 5670 with HDMI to TV = Happily boots but says no keyboard attached and so keeps rebooting itself (same as scenario 2).

There is something about the graphics card combo with the keyboard it seems. I think I'm going to have to pick up a cheapo speaker to connect and see if there are any beeps when the gfx card is in.

Thanks for any help,

Lewis


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 Post subject: Re: Low power causing problems booting?
PostPosted: Wed Jun 08, 2011 2:05 am 
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Joined: Thu May 12, 2011 7:47 pm
Posts: 43
Location: Norway
You should have plenty of power: 35 W processor + 65 W graphics + 20 W for mobo and RAM + up to 20 W for a HDD (max startup power for a 3.5" HDD) => not more than 150 W.

One issue I've seen occasionally is that the BIOS screen doesn't show up over the HDMI output - I get just a blank screen until the OS loads. It depends on the graphics card, I suppose.

Perhaps you could try the VGA or DVI output?

On the speaker, I suppose you know that you need the kind that plugs into the motherboard.


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 Post subject: Re: Low power causing problems booting?
PostPosted: Wed Jun 08, 2011 2:47 am 
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Joined: Tue Feb 08, 2011 12:44 am
Posts: 36
"One issue I've seen occasionally is that the BIOS screen doesn't show up over the HDMI output"
and how quick the monitor selects the input, I have had that problem too.


"On the speaker, I suppose you know that you need the kind that plugs into the motherboard"

iirc ive used a spare LED across the contacts to see that the pc was beeping on startup


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 Post subject: Re: Low power causing problems booting?
PostPosted: Wed Jun 08, 2011 5:38 am 
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Joined: Mon Jan 11, 2010 8:19 am
Posts: 400
Location: Boston, MA, USA
nzdcoy wrote:
iirc ive used a spare LED across the contacts to see that the pc was beeping on startup
Interesting idea! I don't like beeps but a little light would be nice. I would want to know what the typical speaker impedance and output voltage swing was to make sure the LED doesn't draw too much current?

OP: Have you tried anything other than the HDMI? And plugging the keyboard into a different USB port?

Might be a BIOS bug? Could try flashing an updated BIOS, but mind your warranty. I _think_ it would not be voided?

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 Post subject: Re: Low power causing problems booting?
PostPosted: Wed Jun 08, 2011 6:38 am 
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Joined: Sat May 21, 2011 8:16 am
Posts: 8
Thanks for the replies.

I haven't yet tried a speaker (indeed the kind that plugs onto the mobo :)) - I'm quite surprised the new Mobo didn't come with one to be honest, and sadly I don't have any spares. Maplin.co.uk want £4.99 for one!!

I'm going to try a VGA cable this evening and will report back how that goes. Failing that I'll see if i can get windows installed with the onboard graphics when my DVD drive turns up, then I can put the GFx card in and try again.

Tried the keyboard in different USB ports but it still just came up blank.

I suppose at least I've got to the bios using onboard graphics so the motherboard and cpu are working just fine. i3-2100t was showing 37 degrees which is hopefully about right.


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 Post subject: Re: Low power causing problems booting?
PostPosted: Thu Jun 23, 2011 11:51 am 
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Joined: Sat May 21, 2011 8:16 am
Posts: 8
Just wanted to say thanks for the replied. Got the system working fine in the end. It seems that it's just impossible to get to the bios with HDMI on the video card. There is something causing it to struggle to display until it get's to windows. Ultimately I plugged in another vga monitor to get it started and get windows installed. Now it works flawlessly and happily plays L4D2 on the big screen :)

Once again, thanks for the replies.


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