G/F's System Dead (PSU?)

[alizec]

My girlfriend's computer died recently after having been unplugged for a few days (it worked before being unplugged). When I plugged it back in and hit the power... nothing. I went to make sure the power switch was on in the back, and I caught a whiff of burnt electronics coming from the power supply, which was much stronger when I stuck my nose in it. I assume that's what the problem is...

However, I was wondering if a dead PSU can still power the LED on the LAN port, because when it's plugged in, it does light up. The MOBO looks fine - no apparent shorts or blown caps, and the CPU smells fine though I haven't checked the chip visually. All signs point to the PSU, but I wanted a second opinion before I ordered another one.

Her old one was a generic 420w PSU... would either of these be okay to replace it:

http://www.newegg.com/Product/Product.aspx?Item=N82E16817153023
http://www.newegg.com/Product/Product.aspx?Item=N82E16817159040

Thanks.

 

[akhilles]

I haven't checked the chip visually. All signs point to the PSU,

Makes no sense to me. How would you know that? Check the chip. While you're at it, check EVERYTHING.

 

[Onus]

No, neither of those would be good. Coolmax is on tier-5 ("Do not buy") of the PSU listing at http://www.tomswiki.com/page/Tiered+PSU+Listings?t=anon, and that particular Thermaltake is on tier-4. Choose one from tier-3 or better. If your budget is limited, check out a model from FSP. They're on tier-3 and you can get a 450-500W model for around $60.

 

[alizec]

No, neither of those would be good. Coolmax is on tier-5 ("Do not buy") of the PSU listing at http://www.tomswiki.com/page/Tiered+PSU+Listings?t=anon, and that particular Thermaltake is on tier-4. Choose one from tier-3 or better. If your budget is limited, check out a model from FSP. They're on tier-3 and you can get a 450-500W model for around $60.

$60 is a bit out of her price range, and her PC isn't exactly top-of-the-line. She wanted something for $25, but she grudgingly accepted my advice to go up to $50 with shipping + taxes included if I found a good one. Not that PSUs aren't important (I learned that lesson the hard way with 3 blown PSUs in a previous build), but surely there is a good, cheap solution. She already owes me about 4 months of back rent and about the same amount in loans I gave her for school, so it's a situation where she's broke and I'm barely getting us by until she gets her nursing degree.

Her computer would probably fall in line with tier 4 on that list, actually:

Tier 4 is recommended for stock or low power systems if Tier 3's are more expensive or are not available.

Thanks for the link, though. I'll go back to newegg and see if I can locate anything better that's in my price range. PSUs are one area I'm not very comfortable with, so it'll also be helpful as a reference for future builds. However, it's a bit odd to me that a PSU with 1300+ customer reviews and a 5/5 rating on newegg would be in tier 4 (not recommended), as usually a bad product would show its true nature in the face of so many opinions. I'm actually using a tier 5 PSU (Rosewill) on this machine and have been for a while. Who knew? Runs fine...

The reason I didn't check the chip visually is that the smell of burnt electronics is definitely not localized there. It would be a pain and further risk to the CPU to remove everything and freshly install the fan/HS, and the circumstances surrounding how the computer died don't really fit with a blown chip. There were no warning signs - it was just plain dead when I plugged it back in and hit the switch. It seems it would have at least powered on for a split second, or perhaps even beeped to let me know the cause of the issue... I suppose anything could happen, though.

Thanks MrsBytch. It seemed obvious, but I needed someone else to say that. So I assume a PSU can be blown and the LAN light still comes on? That was the main cause of my doubt.

 

[jsc]

The LED on the ethernet port is fed from the 5 volt standby output. On every PSU schematic diagram that I have seen, the 5vSB output is electrically separate from the main power outputs.

For that matter, every PSU outputs a control signal called something like "PSGood" or "PwrOK". Without this control signal, nothing will happen, even if all the power outputs are present.

 

[Shadow703793]

Here is a cheap, good PSU for $30:
http://www.newegg.com/Product/Product.aspx?Item=N82E16817153023&CMP=OTC-RSS&cm_mmc=OTC-RSS-_-Power+Supplies-_-Thermaltake-_-N82E16817153023