No BIOS display on monitor

[bobh]

Hi Folks,

This is my third home built PC courtesy of Rob's
excellent tutorial. The reason I build these things
is basically to learn, and I mostly learn by screwing
things up, so I suspect I will learn a lot with this problem.

Here is what I've got (most everything is off of Rob's
preferred list except the Video Card and the DVD RW.)

Case ANTEC Sonata III
Motherboard Gigabyte EP45-UD3P
Processor Intel Core 2 Duo E8400 (dual-core)
Ram Crucial 4096MB (4GB) PC8500 DDR2 (about 3.00GB usable)
Video Card Radeon HD 4650 DVI using a DVI to VGA adapter
(This is a PCI Express 2 16 bit card)
Hard Drive Western Digital 640GB 7200rpm SATA
DVD RW LG Internal/GH24 Serial ATA

On first boot my screen is not getting input. The box powers up and I can
see read activity for my DVD drive, but no BIOS output is appearing.

The weird thing is that the CPU fan budges a little but doesn't spin.
(I saw in a post about a similar problem that this is normal and
the fan should kick in after a few minutes.) The fan for the box is spinning,
as is the fan for the video card.

I reset the video card and double checked the CPU fan plug and they seem
okay.

Re-reading the mobo spec there is a mention of the ATX_12V_2X4 power plug
which looks like it is an alternative to the ATX 24 plug. The documentation is
vague as to whether both need to be plugged in or just one.

For the moment I only have the ATX 24 power connected.

I can't find any combination of plugs from my Sonata box that are appropriate for the 2X4 plug.

Regards,

Bob

[zburns]

Part of Bob's post: Re-reading the mobo spec there is a mention of the ATX_12V_2X4 power plug
which looks like it is an alternative to the ATX 24 plug. The documentation is
vague as to whether both need to be plugged in or just one.

Hey Bob,

I have sonata III case and 500 watt PSU. Your 500 watt Earthwatts PSU should have a 4 pin plug with what looks like 4 # 18 wires (two yellow blues, two blacks) coming from the PSU.

Plug in that 2 x 4 plug on your mobo. Your install manual has a schematic diagram will show the proper connector and it will be labeled. But you know all this if you are on your fourth build.

This connector does not take the place of the 24 pin connector. While they will not say it (gigabyte), that extra connector is there to provide a set of extra # 16 (or # 14 or # 18) wires to carry the extra current that the +12 volt rail must supply for the more powerful CPU's and the rest of the mobo circuitry. The PSU connectors have a limit as to the wire size that will fit into them -- this is the only plausible reason for the extra connector, and it makes perfect sense.

[bobh]

Hi,

Thanks for the quick response! It looks like I have two
four-pin plugs both marked P2. They have two black wires
and two yellow (with black stripes).

The ATX_12V_2X4 receptacle for the mother board has
eight pins so I was able to plug both in.

However, before I power this up I want to make
sure I'm doing this right.

The right side of the receptacle (looking down from
the mobo layout schema) has four pins: two square sockets
and two bevels which matches on P2 plug appropriately.

The left side of the receptacle pin has two square and
two beveled sockets. The other P2 plug is all beveled
and fits.

Do I need both or should I unplug the left side? Is there
any downside of having all eight pins receiving power?

Thanks,

Bob

[bobh]

I got impatient and booted the system up with both power plugs.
The CPU fan started immediately and I was able to get the BIOS
display.

Interestingly without the additional power the power switch would
not power down correctly.

I have a software OS problem now, but I will post that in
another thread.

Thanks,

Bob

[zburns]

Any chance your antec "booklet" tells you that you have two 4 pin plugs and tells you what they are for. Since there are two plugs, it would be nice (comforting) to know what they say in the Antec Sonata booklet.

Should be no downside to both being plugged in; however, I would like to know how Antec describes each of them.

[bobh]

The out-of-the-box Antec documentation is very minimal and doesn't explain much, so one is left to guess based on mnemonics and the physical configuration of plugs. One of the reasons I build my own PCs is because of Antec boxes which makes servicing so easy.

[zburns]

I would keep on buying the Antec Sonata, my reason being minimal dust intake because of the door-- cannot prove it but just seems that way. I looked up their manual for Sonata iii and what I found was what I got with my case in May 2008. Could be the same as yours?

Glad your problem was one of omission rather than a real mistake.