Broken PC/Buying advice

Lem123

Lem123

Lem123

Associate
Joined
31 Jul 2014
Posts
15
Hi

First post here, but been a lurker, and overclockers customer for many years. I used to be fairly knowledgeable around PC-building - but things have moved on a lot and I've totally lost touch... so here's my problem that I hope you can help with..

Specs..:
AMD Phenom II X3 Tri Core 720 2.80GHz OVERCLOCKED@ 3.30GHz
Gigabyte GA-MA790XT-UD4P Motherboard
Corsair Dominator 4GB DDR3 XMS3 PC2-1600C9D TwinX (2x2GB)
Asus ATI Radeon HD 4870 Dark Knight 1024MB GDDR5 PCI-Express Graphics Card
OCZ ModXStream Pro 600w Silent SLI Certified Modular Power Supply
Seagate Barracuda 7200.12 500GB SATA-II 16MB Cache
Windows Vista Home Basic 64-Bit

My PC of 4/5years has stopped working.. Turning it on, the HDD/CDrom and fans all start up (except Gfx card) - but the monitor stays blank. But oddly - been unable to turn it off by holding down the power switch -had to instead flick the switch on the PSU. This used to work ok.
The fans all seem to run at a slow speed too.

So.. thought 'easy - looks like the fan on the gfx card has failed and the GPU has fried' - and bought a new gfx card...
Sapphire Radeon R9 270

Now with the new one - gfx card fans start ok - but still no display and won't turn off.
Tried clearing the CMOS - no effect, and de-dusting/re-seating the connectors and RAM - no effect, unplugging as much as possible - no effect.
Not sure if it helps, but some fans are powered from the mobo, some direct from the PSU - all work.

So, and this is the awkward bit- I don't really have the time right now to relearn how to diagnose this myself and possibly to replace any central components so I'm looking for a bit of help in whether these symptoms scream 'PSU!' or 'Mobo!' - so far the info I've found seems to indicate it could be either - or the CPU.. I don't have a multimeter or spare PSU hanging around to check further.

If its looking pretty certain what part is the problem, I may look at replacing it - but given its age and my time, I'm also just thinking about replacing the whole system instead - so will be looking for advice on what to get to give good value for money that fits well with the Sapphire gfx card I bought. Use will be for casual-gaming.

Many thanks for your time.
 
Last edited:
Hi Lem, welcome to the forum.

When monitor powers on, do you see a logo appear or anything appear on the screen for a few seconds?
 
Danny75 said:
Hi Lem, welcome to the forum.

When monitor powers on, do you see a logo appear or anything appear on the screen for a few seconds?
Click to expand...

Not a bean. Oh, there's no audio too, so I don't think its the monitor at fault. There isn't the usual variation of fan speeds I usually hear on a good startup.
 
Don't hit me.......

Have you checked the video cable at both ends, tried a different video cable, and tried a different monitor? :)
 
Hehe - and now the funny part.. I may have some.. but it'll be in the loft with all my other PC bits/tools - but I have a bit of a wasp problem up there right now - so I'm not gonna go and look until that's sorted!
 
Lem123 said:
Just tried the monitor plugged into my laptop - works fine.
Click to expand...

How about unplugging everything from the back of the PC, and only plugging back in the power cord and keyboard, and trying? Does the keyboard display a post signal at all? Some (or most) have a light that flashes and then settles on.
 
Danny75 said:
How about unplugging everything from the back of the PC, and only plugging back in the power cord and keyboard, and trying? Does the keyboard display a post signal at all? Some (or most) have a light that flashes and then settles on.
Click to expand...

Keyboard shows nothing - no lights flash - although I forgot to mention earlier, other USB devices seem to get power - ie. my USB wifi adapter lights up.

This and case fans that are powered from the mobo running makes me think power is getting to the motherboard.
 
I don't have a spare keyboard (outside of the loft!) but tried other usb ports - and still nothing on the keyboard. It normally has a backlight on the keys, which is not lighting up too - but strangely enough it does have a USB pass-through, and on plugging my wifi adapter into that on the keyboard, the wifi adapter does get power.

All fans start up including cpu fan except the gfx card fan? id probably look at the gfx card, you got another pc you can test it in or a spare gfx card lying around?
Click to expand...

I already tried a new gfx card as per the original post
 
I had a similar problem to this on my old system, it would power up OK but zero video out, also, tellingly, the fans ran at full speed constantly whereas before they would spool up to speed on switch on, then immediately drop RPM's back. In my case it was the PSU, one of the rails had failed (there's three I believe, 3.3v, 5v & 12v, maybe -12v too?) so some simple components where working (fans, USB power) but not the main system. Could you borrow a PSU from anybody??
 
Sorry, I don't have another PSU to try - although I do think that's a good contender for the cause of the problem too..

Thanks for all the help in tryingto solve it, but as I suspected, it seems there isn't an obvious answer to this without me having to try replacements parts - so I think I'll be going down the route of a replacement system. I contacted Overclockers and they said they could send me one without a gfxcard (and appropriate cost reduction) - so I think I'll do that. Any suggestions on what processor would be appropriate with my new gfx card without causing an obvious bottleneck anywhere?
 
Depending on budget, something like an AMD 6300/8320 for lower budgets, a bit more the i5 4690k
 
I'd still go 4690. What is your max budget for this upgrade? If you tell us, we can spec you and then you can give the list to OcUK who will build it for a small fee
 
I think around £600.. want to include Win 8 (may as well have an OS upgrade with it) and would also like a SSD for the OS (I can use my old HDD for other stuff).
And as mentioned already have the gfx card.

Not sure how much Ram - in the past I've always gone for the standard at the time (seems to be 8gb now?) - but its always seemed to have been one of the things that I seem short on as the PC gets a little longer in the tooth.
 
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