Overheating?

I live in SoCal, it's warm but it's not the tropics. However, I generally find I can't use my PC in the daytime. In the cool of the early morning and evening it works fine. In the daytime, when the house is warmer, I get video issues issues and sometimes the screen is completely dark although the monitor has power. Booting into safe mode fixes it. Opening the case helps it a little also. Can anyone suggest trouble-shooting steps? I'd really like to be able to use the computer in the daytime. Thanks

Unfortunately, you told us nothing about your computer. Note it is the case's responsibility to provide an adequate supply of cool air flowing front-to-back through the case. I generally recommend a case with at least two large (120mm or larger) fans, one in front drawing cool air in, and one in back (in addition to the PSU's fan) exhausting hot air out. You need to inspect the case to ensure it is free of heat trapping dust, the cables are routed to minimize impacting flow, and if the case will support more or larger fans. However, if the ambient (room) temperature is too high from the start, no amount of fan will help. What happened in July and August when it was hotter still?

July and August - all was well. However, I recently had to move my PC into the upper rooms and I guess they're warmer. So is it likely overheating? I wondered if there was a way to check internal temperatures to see if it exceeded the operating range. The computer is a Dell 8300, about 7 years old. It's standard in every way except I had this issue about 5 years ago and replaced the video card thinking that it was broken but I'm thinking it may be the heat. The wiring n the casing seems ok but to be honest I'm not an expert. Room temperature isn't warm, maybe 70 degrees F.

I wondered if there was a way to check internal temperatures to see if it exceeded the operating range.

There are many ways. Here is my canned text on that:

Your motherboard utilities disk should have a monitoring program (or check for a more recent version on your motherboard or PC maker's website). If none, I recommend CoreTemp for newer Intel and AMD64 CPUs, or RealTemp for Intels. SpeedFan is a great and popular alternative, or you can try Motherboard Monitor. Unfortunately, I have found that these programs often have problems properly identifying and labeling the sensor they are reading. The temperatures shown are as accurate as the inexpensive, low-tech sensors will allow, but it may say System Fan instead of CPU Fan. Fortunately, the programs do allow you to edit the labels, so I use Everest to verify the temperatures (as it is able to put sensor to label correctly), then edit the label in the monitoring program. In Everest, look under Computer > Sensor, then wait a couple seconds for the readings to appear. Unfortunately, Everest does not minimize to the system tray to show real-time temperatures, otherwise, you could use Everest instead of the others.

Thanks for the help, all is well I think. I've always blown out my case but on my PC there's a flap at the front which hides 2 USB's. I rarely use them there and had overlooked the grill under the flap which pulls in air. I spotted it today and blew it out. It's mid-day, pretty warm and my PC is silent Happy it seems to be ok but feeling a little daft I hadn't seen this before

It is not likely a clogged USB port would cause heat problems. It is more likely just the cleaning of the case did it. As far as feeling daft, don't. There are all sorts of nooks and crannies for dust to get trapped in. Still, you need to monitor your temps. I have CoreTemp running full time and it puts my CPU temperature down in the system tray (next to the clock) so I can always keep an eye it. When I see it consistently staying a bit above normal, I know it is time to give my filter a washing. And for the record, I will never buy a case again that does not have a removable, washable air filter. With dogs and grandkids running about, bringing in and stirring up dust, I used to need to take my computers outside at least 3 or 4 times a year for a good cleaning. Now, using cases with filters, maybe once a year.

Good idea on the filter, regarding the grill at the front. It's probably about 6 square inches. Cleaning that seems to have made all the diffrence

6 inches? That's different. If that were clogged, that could certainly restrict a significant amount of air intake. I bet you never forget to check that again!