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Corsair AX850 vs Thermaltake TPG-850M vs Cooler Master RS800

3K views 13 replies 4 participants last post by  Zazula 
#1 · (Edited)
I'm after a good quality 800-850W PSU. The PSU-selection sticky suggests Thermaltake TPG-850M and Cooler Master RS800. It doesn't mention Corsair AX850, but it is a 80 Plus Gold Certified PSU in this wattage class. Now for my questions:

1. I can get the AX850 here for 185-190 euros, while the RS800 is at 177 euros. I lean more towards the AX850, so I'm asking: Is it really worth the higher pricetag?

2. I can't seem to find the TPG-850M here, and I'm wondering: Am I really missing something much more exceptional than the other two PSUs in my short list?

3. Is there any other 80 Plus Gold/Platinum Certified PSU in this wattage class that is worth looking into?

Many thanks in advance! :smile:

PS My GPU is an 8800GT that needs a 6-pin PCIe adaptor. I hope all of these PSUs are compatible, aren't they?
 
#5 ·
I've bought and installed the AX850. It replaced an FSP Epsilon 700W (FX700-GLN) psu. I have some good news and some —really worrying, I'm afraid— bad news after that...

The good news is that:
  1. A sata/raid pci-e card I have works now far better than how it used to under the previous psu; it boots faster, it never hangs, it now allows hot-plugging the way it was supposed to. This could be either due to the motherboard current being better now, or due to the sata current being better (I was using all 6 sata connectors on the previous psu).
  2. My usb buses run far better now and everything I have hooked up works the way it is supposed to; under the previous psu most of the times not all usb ports were working simultaneously and my internal multi-card reader (usb-hooked) used to be erratic in its operation.
  3. The 3.3V, 5V and (a bit less) 12V voltages are outstandingly stable, with almost no noticeable fluctuations.
Now for the bad news (please bear in mind that my testing conditions are identically identical, to the level of processes running, ambient temperature, time of the night or day, my mood or what have you):
  1. My CPU runs much hotter now (although no other changes have been made).
  2. My CPU cannot even conclude the OCCT test that it could finish hands-down under the previous psu.
  3. The Vcore fluctuates a lot, irrespective of the bios setting.
First let's see how the computer handles a very simple and light stress-test (by Everest). Before (i.e., with the FX700-GLN), the CPU had a 34°C idle temp and a 46°C mean-stress temp:

Now (i.e., with the AX850), the CPU has an idle temp of 38°C and a mean-stress temp of 50.5°C (you'll also notice that all temps are higher in comparison to the previous test):


But the really BAD news is what happens when I run the OCCT 'power supply' stress test. :sigh: First let's see how the old psu performed; here are the CPU1 temps (CPU2 temps were better):

And here is the Vcore for the FX700-GLN:


Now, with the AX850 the same OCCT test hangs at 4-9 minutes! I've been only once able (after umpteen tries) to conclude the test. Here are the CPU1 temps (in this case the CPU2 temps were actually WORSE that the CPU1 ones you're seeing):

And here's the Vcore for the AX850:


I believe that what I'm experiencing with my cpu temps after installing a better psu is highly unnatural, unexpected and abnormal. Please advise — thanks in advance.
 
#6 ·
Are you sure you did not bump the heatsink by accident whilst installing the new PSU? A reapplication of thermal paste would be my first suggestion. Also check the idle temps in the BIOS for better accuracy.
 
#7 · (Edited)
Well, I was thinking I'd better reapply the thermal paste just in case (although, to the best of my knowledge, I didn't kick, hit or move the heatsink while working). But it's no biggie doing that just to be sure and on the safe side — and getting this parameter out of the way, that is. In any case, some freshly applied AS5 can't do any harm! :smile:

Plus I forgot to mention the last one of the worrying bad news after installing the AX850 — and this one I really cannot figure out whatsoever: My main monitor (the second one gets on only after Windows kicks in) got extremely slow at waking up after moving the mouse (we're talking about a 45-60 seconds delay here!) and it shows nothing for the first minute or so of the booting process (because it gets no signal, that is). Now, what about that? :4-dontkno

PS This thing with my monitor started happening just after I closed the case, with the new psu installed.
 
#10 ·
Plus I forgot to mention the last one of the worrying bad news after installing the AX850 — and this one I really cannot figure out whatsoever: My main monitor (the second one gets on only after Windows kicks in) got extremely slow at waking up after moving the mouse (we're talking about a 45-60 seconds delay here!) and it shows nothing for the first minute or so of the booting process (because it gets no signal, that is). Now, what about that? :4-dontkno

PS This thing with my monitor started happening just after I closed the case, with the new psu installed.
OK, this got rectified; I was away from home for some days so I left everything off the mains for all that time. When I reconnected them on my return, everything started working correctly — no monitor switching-on or waking-up issues ever since.

Sorry for being slow on the temp issues, but I've been quite overwhelmed with work in the meantime; I'll keep you posted as soon as I reapply the thermal paste and begin testing.
 
#9 ·
Do you have sufficient case ventilation? The AX850's fan won't kick on until the PSU itself requires it so can't really be used to exhaust hot air from the case like a cheaper supply with a constantly-on fan can.

< 20% load -- fan off

20% to 50% load -- fan slow

> 50% load -- fan high

My AX850's fan almost never spins unless I'm in a 3-D game or am running a benchmark program.
 
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