Is there any other simple and two left feet way to test the PSU.
Not that I'm aware of, at least not without test equipment. The PSU fault, if there is one, might only occur at higher loads. You would have to simulate those conditions before the fault manifested. The ATX PSUs also have multiple rails providing various voltages to the motherboard, drives, etc. Each of those rails would have to be stress tested individually on a test bench. It's not worth the bother. PC PSUs are basically disposable items.
Before you consider replacing the PSU, you might want to check for compatibility: some Dell motherboards/cases have used non-standard PSU connectors or sizes.
Having now consumed my tea I have used SisoftSandra and this has come up -- Warning W2519 - One of the mainboard fans has failed or is spinning too slowly. This should appear only if the mainboard has a temperature-monitoring sensor installed and the fans have tachometers. If the fan is speed controlled, this may be normal.
Fix: If the fan is not speed controller, power down the system immediately. Open the case and check that all the fans are working and check whether components are unusually hot inside. Make sure the components have good all-round ventilation.
Hmm. not sure that warning is very trustworthy. The fan controllers on a motherboard are usually generic devices. The controllers can support multiple fans than might not actually be present on the motherboard. It doesn't bode well that the SiSoftSandra tool cannot distinguish between a failed fan (or a missing fan) and a fan that has simply slowed.
It's not much use for Windows, but the de-facto Linux software for fan control and monitoring is called lmsensors.
http://lm-sensors.org/ It will be a standard tool included on those stress-testing Live CDs linked above. Worth a look. This is the sort of thing it reports:
w83627ehf-isa-0290
Adapter: ISA adapter
VCore: +1.33 V (min = +0.00 V, max = +1.74 V)
in1: +11.88 V (min = +10.08 V, max = +13.46 V)
AVCC: +3.30 V (min = +4.08 V, max = +2.93 V) ALARM
3VCC: +3.31 V (min = +4.08 V, max = +4.08 V) ALARM
in4: +1.64 V (min = +2.04 V, max = +2.04 V) ALARM
in5: +1.65 V (min = +1.52 V, max = +1.53 V) ALARM
in6: +0.23 V (min = +6.53 V, max = +6.50 V) ALARM
VSB: +3.33 V (min = +4.08 V, max = +4.08 V) ALARM
VBAT: +0.00 V (min = +4.08 V, max = +4.06 V) ALARM
in9: +0.07 V (min = +2.04 V, max = +1.53 V) ALARM
Case Fan: 0 RPM (min = 55 RPM, div = 128) ALARM
CPU Fan: 1864 RPM (min = 0 RPM, div = 4)
Aux Fan: 0 RPM (min = 0 RPM, div = 128)
fan5: 0 RPM (min = 0 RPM, div = 8)
Sys Temp: +36°C (high = -1°C, hyst = -1°C) ALARM
CPU Temp: +30.0°C (high = +80.0°C, hyst = +75.0°C)
AUX Temp: +48.0°C (high = +80.0°C, hyst = +75.0°C)
(as an aside)
Silent PCs are interesting. These have sexed-up passive cooling systems that have to be closely monitored, especially during the building stage. There are quite a few tricks to keeping everything cool. For example, the CPU core voltage (VCore) can often be dropped below the voltage specified by the chip maker. The specified voltage is only a guide. A lower core voltage can make the CPU run cooler, etc.. However, drop the voltage too low and the CPU becomes unstable. Also one of the symptoms of a failing PSU..
cheers, a