"No signal detected"

A few days ago I did some cable management and cleaning in my PC I had to take out the motherboard, RAM & graphics card. When I booted it up I had no initial problems, then I noticed games weren't running at smooth frame rates & they were lagging quite a bit. I did a system check, with "dxdiag" and it showed only 1gb of RAM although 3gbs are installed. I found a thread on a forum about this suggesting that the RAM cards were in opposite slots after the work I did. I swapped them over, but then got 'no signal detected' on the monitor: swapped them back again and still 'no signal detected'.
I've checked for loose cables & reseated the graphics car twice: still no joy.
I put this pc together myself. Specs below:
Asus M5A78l-M USB3
AMD athlon x3 3.4ghz
Radeon 6770 1gb GDDR5
500GB hard drive

Can anyone please help me with this?

Discussion is locked
Reply to: "No signal detected"
PLEASE NOTE: Do not post advertisements, offensive materials, profanity, or personal attacks. Please remember to be considerate of other members. If you are new to the CNET Forums, please read our CNET Forums FAQ. All submitted content is subject to our Terms of Use.
Reporting: "No signal detected"
This post has been flagged and will be reviewed by our staff. Thank you for helping us maintain CNET's great community.
Sorry, there was a problem flagging this post. Please try again now or at a later time.
If you believe this post is offensive or violates the CNET Forums' Usage policies, you can report it below (this will not automatically remove the post). Once reported, our moderators will be notified and the post will be reviewed.
- Collapse -
Clarification Request
Since you mention ...

that you moved things around to clean I am moved to ask what you used for the cleaning and why you thought you needed to remove components rather than dusting and blowing the air around them.

If you got busy with a brush it is possible that too stiff bristles damaged the RAM slots. It is also possible that loose bristles or something else got into the slots and are preventing full seating of the modules.

It is also possible that the graphics card isn't fully seated and also possible that the monitor cord is loose or damaged.

What happens when you only use ONE RAM module? Check each of them one at a time to see if one has a problem. If none have problems try them in differend configurations that your motherboard manual shows are acceptable.

- Collapse -

Already ready reseated graphics card around 3 times, tried using one RAM card tried using different RAM cards. The motherboard wasn't properly screwed in so I took it out and screwed it back in also checking the VGA cable. I didn't use a brush and also did blow air in whilst the I had everything out of the case

- Collapse -
The next steps.

1. Try another monitor.
2. Try another cable.
3. Try another graphic card.


- Collapse -
Did you happen to ...

take the CPU out to refresh the thermal paste between it and the heatsink?

I have see CPUs that got dropped during the process and bend a few pins that went unnoticed and got bent flat when re-inserted. Those pcs also gave a cheerless "no signal" alert on the monitor.

If you did remove the CPU do check it because the good news is that if you are very careful you can use a sharp knife blade to straighten the bent pins.

If you didn't mess with the CPU try a different video card and cable.

CNET Forums